"الحمد لله" is literally translated "Thanks to Allah". And it's only used in that context. Ex. Thanks to Allah I am fine. "جزاكم الله خيرا" literal translation would be "May Allah bless you". It's used when someone does something good for you, and it's like a prayer where you say "May Allah give you" or "May Allah bless you for what you did". "شكرا" is simply "Thank you". Hope this helps ^^.

Just say شكرا الحمد لله is not a "thank you" equivalent. It means "Thanks God" and in colloquial speech it means "I'm good" or "Things are going well". So you see, it has nothing to do with "thank you". جزاك الله خير means "May God reward you well". You could use it as a "thank you", but it sounds rather religious and people will probably assume you're a Muslim if you use it alot, because it tends to be used more by the religious people. Unlike common expressions like الحمد لله and ان شاء الله which are used by everybody, جزاك الله خير tends to be used mostly by religious people.

May Allah reward you immensely

جزاك الله خيرا is like a "thank you" but it has extra meaning which is "May Allah (God) reward you." And it is said by Muslims to other Muslims when they do something good whether it was towards them or towards others.