All of it is grappling.
The question you are really asking is, which specific rule set has greater possibility space? Generally, this means the more 'open' a rule set is, but this is not always necessarily the case; specifically, in cases where there is a certain tactic or set of tactics opened up that are both relatively straitforeward and disproportionately effective. Ground fighting in MMA for instance; it is a more 'open' ruleset than grappling without strikes, but you do not necessarily need to have a highly aretic game developed to be able to sub people in order to finish them anymore, you 'just' need to be able to ride them and control limbs, and finish them with ground and pound.