The SRTH reflector is more mirror-like (less aggressively stochastic) and suited (designed) to accept Lamp Assemblies with short (more 'point-source') filaments. The N1, N2, N4 & N5 are the primary Lamp Assemblies.
The N62 is a bigger filament but it's not as much of a "bar" as the likes of the MN15 or MN16, MN60 or MN61.
The most ideal Lamp Assembly for the SRTH in my opinion is the N2 followed by the N5.
The N1 for two-SF123A bodies is 65lu/60min
The N2 for three-SF123A bodies is 105lu/60min
The N4 for B65 NiCad battery stick bodies is 60lu/60min (discontinued)
The N5 for for 8AX/8NX is 110lu/50min
The MN15 for three-SF123A models is 125lu/60min
The MN16 for three-SF123A models is 225lu/20min
The MN60 for four-SF123A models is 225lu/60min
The MN61 for four-SF123A models is 350lu/20min
The T Series TurboHead is a discontinued Extended Range model with a 3" diameter reflector and uses the N lamps like the SRTH.
The N62 had it's own TurboHead with a slightly different reflector finish again.
The T-62 TurboHead was a TRTH (Threaded Rim TurboHead) and it was featured on most of the 12PM/12ZM/LeopardLights.
This gives you an idea of how much larger a T TurboHead is compared to the SRTH even though on paper there is only 1/2" difference in diameter.