"MLPA" is short for the Marine Life Protection Act, which is the legislation requiring California to have a marine protected area network.
"MPA" is short for marine protected area, which is a named, marine or estuarine areas that has been designated to protect or conserve marine life and habitat.
"SMR" and "SMCA" are short for state marine reserve and state marine conservation area, respectively. SMR or SMCA refers to the specific type of MPA. SMR is an area that prohibits all extractive activities (with exceptions for scientific studies). SMCA is an area the may allow some type of extractive activity including recreational and/or commercial fishing, however each area is unique in what it allows.
Additional terms and definitions used in MPA Management.