p28? ECU codes

I was wondering what the diffrence between like a p-28 "brain" or whatever, vs. like a P-72 (if thats right) brain.

I was wondering what the diffrence between like a p-28 "brain" or whatever, vs. like a P-72 (if thats right) brain.

That ECU code determines which car/motor the ECU is for.

ECU : YEAR Model
PG6 : 88-89 Integra (all makes)
PM5 : 88-91 Civic/CRX DX
PM6 : 88-91 Civic/CRX SOHC Si
PM7 : 89-91 DOHC ZC (JDM 'EF' ECU)
PM8 : 88-91 CRX HF
PR2 : 89-91 ZC (Euro)
PR3 : 89-91 JDM B16A EF8/9
PR3 -J00 or J51 : 92 JDM Integra B16A EF8/9
PW0 : 89-91 JDM B16A EF8/9 DA6-XSi
PR4 : 90-91 Integra LS/GS
PS9 : 88-91 4 door Civic EX Auto
P05 : 92-95 OBD-1 Civic CX
P06 : 92-95 OBD-1 Civic DX
P07 : 92-95 OBD-1 Civic VX
P08 : 92-95 OBD-1 Civic D15 JDM
P0A : 94-95 OBD-1 Accord EX
P13 : 93-95 OBD-1 Prelude Vtec
P14 : 93-95 OBD-1 Prelude Si (non Vtec)
P27 : 92-95 OBD-1 EG JDM Civic 1600 sohc
P28 : 92-95 OBD-1 Civic Si/Ex
P30 : 92-95 OBD-1 DelSol DOHC Vtec Si/EG SiR
P54-G31 : 1997 Honda Accord 1.8 LS
P61 : 92-93 OBD-1 Integra GSR
P72 : 94-95 OBD-1 Integra GSR
P72 : 96-00 OBD-2 Integra GSR
P73 : 96-00 OBD-2 Integra Type-R (JDM & USDM)
P74/75: 92-95 OBD-1 Integra LS/GS
P75 : 96-00 OBD-2 Integra LS/GS
P2N : 96+ OBD-2 Civic HX Coupe
P2P : 96+ OBD-2 Civic EX Coupe
P2E : 96+ OBD-2 Civic DX Coupe
P2M : 96+ OBD-2 NZ Civic SOHC VTEC
P2T : 99+ OBD-? Civic Si Coupe
P5P : 97-00 OBD-2 Prelude Type-S (JDM ECU)
PBA : 97+ US Acura 1.6EL
PCT : 98+ JDM ITR / CTR
PCX : 99+ OBD-? S2000

SOHC vs DOHC, fuel maps, timing maps, knock sensor, secondary butterfly for IM.

wow, that was very helpful, thanks guys