kef 102 and 103 differences

does anyone know how they are different or do they have similar sound?
Samuellaudio, I have both pairs in my surrounds. Thats if you talking about the ref from the late 80s to early 90s?
yes. I think they can be used for surrounds, but do they match 104, 105? (many versions)
Yes, they are good. I have the 104/2 and use the ref 102 and 103 in the surrounds.

They do match well. In fact, the tweeter in all 4 of those mentioned speakers use the same tweeter. The tweeter is just differently shaped for the 104 cause its an inside install.

The midrange is also the same exact in the 103 and 102. The only basic difference is the 103 has one woofer inside.

Hope that helps.