“致敬”is usually used as a verb in Chinese, it means show respect to somebody or something
For example. "我向这位英雄致敬" I showed my respect to the hero.
“敬礼”(salute) is considered as a movement/action of showing respect to somebody/something. Especially used in describing something about military.
e.g. “士兵们向军官敬礼” Soldiers saluted to the officer.
“行礼”also means "salute", but you can use it in more occations, it means a movement/action when you meet a older/respectful person.
e.g. “我向老师行礼” I saluted to my teacher.
So that's it. If you have further questions, tell me as you like.