They are more related to manufacturers dates of manufacture or "MK numbers ".
Q is separate from M not joined to it there is also a J version .
Do not confuse this with British nomenclature which is to do with specifications like BC550 A-B- C indicating different hfe (gain ) in other cases different voltages and so on..
All the non UK types that had M or Q markings had the same specifications right across the board in my equivalents books.
American -2N BJT,s did have slight variations in say =2N 2369 and 2N2369A but not always gain sometimes a higher working voltage as did British BD series.
But no ---so far I cant find any published difference in M & Q as related to the SA/SC series of BJT,s although it could be related to the die ( NOT the pin out ) but shape dimensions of minute variations in a later mark number.
Q is separate from M not joined to it there is also a J version .
Do not confuse this with British nomenclature which is to do with specifications like BC550 A-B- C indicating different hfe (gain ) in other cases different voltages and so on..
All the non UK types that had M or Q markings had the same specifications right across the board in my equivalents books.
American -2N BJT,s did have slight variations in say =2N 2369 and 2N2369A but not always gain sometimes a higher working voltage as did British BD series.
But no ---so far I cant find any published difference in M & Q as related to the SA/SC series of BJT,s although it could be related to the die ( NOT the pin out ) but shape dimensions of minute variations in a later mark number.