You asked
Pentax k s2 vs pentax k s1?
The two bodies are very close. Both have a 20.1-megapixel APS-C sensor, in-body stabilisation and the Pentax K mount, so they take the same lenses. The main differences are age and build. The Pentax K-S2 came out in 2015 and is listed as small and weather-sealed, with a flip-out screen. The Pentax K-S1 dates from 2014, and its page doesn't mention those features, so I'd check the spec before assuming it has them.
If you're after a sensible everyday kit on either body, I'd start with the Pentax HD DA 18-50mm f/4-5.6 DC WR RE for general use. For a walk-around zoom that covers more, try the Pentax HD DA 16-85mm f/3.5-5.6 ED DC WR. For a small, sharp prime, the Pentax smc DA 35mm f/2.4 AL is a good pick.
Written by Claude from this site's pages.