разница между "protect" и "defend"

Эти слова ни разу не синонимы. Совершенно разные. Просто в русском слово "защита" омоним, поэтому навскидку разница не видна. Но всмотритесь в суть слов, и разницу тут же увидите.

Defend - военно-оборонительная защита, отражение нападения врагов (министерство обороны и т. п.) , область - социально-цивилизационная.
Protect - техническая защита (например, от коррозии, защитное приспособление или устройство защиты электрической сети от перегрузки) . Область - научно-техническая.

Defend и protect имеют значение «обеспечивать безопасность, предохранять от (нападения, травмы и т. п.) . В чем же их различие?

Например, в ситуациях, когда речь идет о нападении врага, чаще употребляется глагол defend, подразумевающий активные действия (вроде борьбы, отпора) .

Примеры: 1. The troops defended the city against the enemy.

2. The boy defended himself against his attacker with a big stick.

Глагол protect обычно не предполагает ответных действий. Он означает, скорее, «охранять, предохранять, прикрывать от чего-либо» .

Примеры: 3. A line of forts was built along the border to pro­tect the country against attack.

4. He raised his hand to protect his face from the blow.

5. In this climate you need a thick coat to protect you against the cold.

Люди, которые на работе имеют дело с опасными веществами, носят защитную спецодежду (protective clothing).

С такими словами, как property, interests, rights, может употребляться любой из этих глаголов, в зависимости от ситуации. Defend предполагает более активные меры по сравнению с protect.

defend /dI"fend/ verb

1 [T] to protect someone or something against attack or criticism:
How can we defend our homeland if we don't have an army?
White blood cells help defend the body against infection.
They are fighting to defend their beliefs/interests/rights.
He vigorously defended his point of view.
The Bank of England intervened this morning to defend the pound (= stop it from losing value).
The Prime Minister was asked how he could defend (= explain his support for) a policy that increased unemployment.
He will be defending (= trying not to lose) his title at the European Championships next week.
[R] I'm going to karate lessons to learn how to defend myself.
I can't afford a lawyer so I shall defend myself (= argue my own case in a law court).
Compare attack.

2 to try to prevent the opposing player or players from scoring points, goals, etc. in a sport:
The defending champion will play her first match of the tournament tomorrow.

defence UK, US defense /dI"fents/ noun

1 [C or U] (a) protection or support against attack, criticism or infection:
The rebels' only form of defence against the soldiers' guns was sticks and stones.
The war has ended but government spending on defence (= the country's army, navy and air force) is still increasing.
When Helen criticized me, Chris came/rushed to my defence (= quickly supported me).
The book is a closely argued defence of (= something that supports) the economic theory of Keynes.
The towers were once an important part of the city's defences.
A good diet helps build the body's natural defences.
See also self-defence.

2 [S or U] (an) argument or explanation which you use to prove that you are not guilty of something:
The judge remarked that ignorance was not a valid defence.
She said that she didn't want a lawyer and was going to conduct her own defence.
All I can say, in defence of my actions, is that I had little choice.

3 [S or U] in some sports, the part of a team which tries to prevent the other team from scoring goals or points:
a strong defence
I play UK in/US on defence.

4 [C or U] in the game of chess, a particular set of moves used by the person playing with the black pieces:
What defence did you use in that last game?

the defence LEGAL
the person or people in a law case who have been accused of doing something illegal, and their lawyer(s):
a witness for the defence
a defence lawyer

defenceless UK /dI"fent.sl@s/ adjective (US defenseless)
describes people, animals, places or things that are weak and unable to protect themselves from attack:
a small defenceless child
a defenceless city
They were quite defenceless against the enemy bombs.

defencelessness UK /dI"fent.sl@.sn@s/ noun (US defenselessness)

defendant /dI"fen.d@nt/ noun [C] LEGAL
a person in a law case who is accused of having done something illegal
Compare plaintiff.

defender /dI"fen.d@r/ US /-d@`/ noun [C]

1 someone who protects a place against attack, or who believes in and supports a person, idea, plan, etc:
The city's defenders were outnumbered by the besieging army.
So far they have found few defenders of their point of view on campus.

2 someone in a sports team who tries to prevent the other team from scoring points, goals, etc:
The Brazilian attack put France's defenders under pressure.

defensible /dI"fent.sI.bl=/ adjective (US ALSO defendable)
able to be protected from attack, or able to be supported by argument:
A city built on an island is easily defensible.
High petrol taxes are defensible on ecological grounds.

defensive /dI"fent.sIv/ adjective

1 used to protect against attack:
These are purely defensive weapons, not designed for attack.
NOTE: The opposite is offensive.

2 too quick to protect yourself from being criticized

3 in a sports event, trying to prevent the opposing player or players from scoring points, goals, etc:
He's currently

"protect"
существительное

1. защита

глагол

1. защищать
2. охранять
3. оберегать
4. защищать
5. акцептовать
6. акцептовать
7. защищать
8. беречь
9. сберегать
10. оплачивать
11. предохранять
12. защищать
13. ограждать
14. сберегать
15. оплачивать
16. сберегать
17. осуществлять протекторат
18. проводить политику протекционизма
19. охранять
20. покровительствовать
21. покровительствовать
22. акцептовать

"defend"

1. не давать биться о борт

глагол

1. защищать
2. поддерживать
3. оборонять
4. оберегать
5. возражать
6. выступать защитником
7. защищаться
8. обороняться
9. запрещать
10. защищать
11. отстаивать
12. оправдывать
13. защищать на суде
14. защищаться
15. оборонять
16. обороняться
17. защищать в суде
18. выступать защитником

protect - защищатьнапример город
defend - от слова defence- защита например в баскетболе защита кольца

Наиболее подходящий вариант: "охрана" и "защита" (см.,

например, статью Шумова П. В. "Соотношение понятий "охрана" и "защита" информационных прав" (21.08.2017): https://center-bereg.ru/h103.html). Возможен также вариант: "охрана" и "оборона".