Got a quality dyno tune a few months back, And the tuner gave me a total of four tunes:
MAF open loop tune
MAF closed loop tune
Speed density open loop tune
Speed density closed loop tune

I am currently running the MAF closed loop tune which has minor cam surge under 2K RPM. With the MAF open loop the cam surge is gone.

What is the difference in open loop, closed loop. MAF vs. Speed density?

 

Open loop, your computer just commands an afr and doesnt care what the o2 sensors think about it.

Closed loop it pays attention to your o2 sensors and adjusts fuel trims.

Maf mode uses your maf to calculate fuel from air coming into the engine.

Ve uses tables to look up the amount of % cylinder filled vs rpm and map to decide how much gas to squirt in. Its not quite as robust as maf mode, but throttle response is generally better imo.