two type of soldier or two types of soldiers? which one is correct? or both of them?
two type of soldier or two types of soldiers? which one is correct? or both of them? and WHY?
AND what's difference between "two type(s) of soldier(s)" and "two kind(s) of soldier(s)"?

Question

Answer

Two types of soldier because soldier is part of a prepositional phrase- we're not counting soldiers but rather types.

correction: it appears that ''types of soldiers" is correct.

Answer

For the first part, it needs to be "two types", because there is more than one type.
For the second part, I'm "99%" sure it needs to be "soldiers".

Regarding "types" vs. "kinds," I think those are interchangeable and do not differ in meaning in any discernible way. Either way, you're dividing up all soldiers, putting them into buckets, and putting a label on the buckets :-).