Below is a list of possible variations of the P.38. This is not a list of what I necessarily consider variations, I just tried to come up with a list of what a P.38 collector MIGHT consider a variation.
Walther
1st variation “0” series with C/N & numbered small parts
2nd variation "0" series without the above
3rd variation “0” series
4th variation “0” series
4th variation “0” series with military grips
480 (rounded lanyard loop)
480 (rectangular lanyard loop)
480 40 added
ac no date
ac40 added
ac40
ac41 (high polish, ac on trigger guard)
ac41 ( high polish with E/WaA359 on slide)
ac41 (high polish, no ac on trigger guard)
ac41 (military finish)
ac42 (waffenamt small parts & numbered mags)
ac42 (without above)
ac43 (early frame)
ac43 (late frame)
ac43 (large “ac”, small “43”)
ac43 (E/WaA359 on slide)
ac43 (straight line)
ac43 (straight line with out of sequence stamps)
ac44
ac44 (FN frame)
ac44 (fnh barrel)
ac43 (FN slide)
ac44 (FN slide)
ac45
ac45 (capital “A” suffix)
ac45 *35
ac45 (fnh barrel)
ac45 (FN frame)
ac45 “c” block, matching
ac45 “c” block, mismatched
ac frame late date
Mauser
byf42 (waffenamt small parts)
byf42 (without above)
byf43 (early frame)
byf43 (late frame)
byf43 (with mixed waffenamts)
byf44 (with all E/135 waffenamts)
byf44 (with mixed waffenamts)
byf44 (standard blued finish)
byf44 dual tone
byf44 all phosphate
ac43 dual tone
ac44 dual tone
svw45 dual tone
svw45 all phosphate
Spreewerk
cyq (211 stamp)
cyq (Walther small parts)
cyq (backward “c” suffix)
cyq (early frame)
cvq (early broken die)
cyq (late frame)
cyq (FN frame)
cvq
cvq “a” prefix serial number
cvq “b” prefix serial number
“0” series
“0” series with FN slide
Double “00”
Mauser Police
byf43 E/L
byf44 E/L
byf44 E/F
ac43 E/F
ac44 E/F
svw45
HP
Swedish
Swedish undelivered
High polish
.30 cal double action
.30 cal single action
Alloy frame
E/359 slide
*35
Military finish
Mod P.38
ac45 “0” series