What is the difference between SP and SPS in Portal version

Hi Experts,

When I check my Portal vesion in System Information,  It is  7.02  SP 13.  I assume it means  Ehp2 of EP  7 SP 13.

But when I check in the PAM ,  for EHP2  EP 7  it is showing SPS levels  but not SP levels.   But why my portal is not showing SPS.

But to check the Compatabilites  for this version.

Can anyone please give me clear difference of it.

Regards,

Raghu