Introduction and newbie question about Capcom v SNK 2

I am Nam Lee, Digital Marketing Manager of HAN Mooncake project. Nice to meet you all
So apologies in advance for this question but the only 2D fighter I ever got into was Street Fighter 2.

I am now trying out Capcom v SNK 2 and I don’t know what the difference between KKK, HK, PPP and HP is.
When I execute a KKK or HK with Ryu the attack looks the same. Same with PPP vs HP.

Are they only different when performing combos or special moves?

I haven’t played in years but certain characters can do special moves with KKK or PPP. For example, Rolentos hop/jump is done with KKK, same with Blankas hop/dash, which both can be roll cancelled.