Sekonic light meter

[iancass]

Is the much difference in the Sekonic L-308B S and X or is it just a matter of tiny incremental differences?

 

[Scooter]

They are just different iterations of the same meter. The X is the latest. The S is the previous one, and the B is older still.
http://camera-wiki.org/wiki/Sekonic_L-308
https://www.photographyblog.com/news/sekonic_l_308x_light_meter

If you want to use it as a flash meter, they are all the same.