Actually on a VA loan there are costs that the seller must pay, they are called VA "non-allowables". After the non-allowables, the seller or the buyer can pay the rest of the closing costs, whatever is negotiated.

With a FHA loan the seller can pay all closing costs or none or some, whatever is negotiated. But unlike VA loans, there are no closing costs the seller must pay on a FHA loan.

Here is a list of some of the VA loan closing costs that the VA does not allow the buyer to pay:
-cost of a termite inspection
-loan processing fee
-loan underwriting fee
-escrow fee
-notary fee
-escrow doc prep fee

Both FHA and VA follow the accepted contract (with very minor exceptions). They both cite "reasonable and customary closing costs". So whatever you agree to in the contract (such as seller pays termite, buyer pays home inspection, seller pays title, buyer/seller split escrow, buyer pays appraisal, etc. is going to dictate who pays what.