Main differences to the Pentax K-30 include a more traditional body design, 120 available body color combinations, higher max ISO range (up to 51 200), compatibility with Eye-Fi cards and the kit lens which Pentax K-30 uses DA L 18-55mm/DA 18-55mm WR lens, while Pentax K-50 uses DA L 18-55mm WR lens (L means Light with plastic mount and WR means Water Resistant).
Among APS-C Mid-Range DSLRs, Pentax K-50 has the smallest body, although is 4mm wider than its nearest rivals Nikon D5300. The body is made from Stainless steel and polycarbonate resin as Canon EOS 700D. Pentax K-50 only has microphone and no audio in as the rivals. Only Pentaxs are provided with Water Resistant kit lens, Pentax K-50 with DA L 18-55mm F3.5-5.6 WR, while Pentax K-3 with 18-135mm F3.5-5.6 WR. The Pentax K-50 price is the cheapest (slightly offer than $500 for body only and less than $600 with kit lens at the end of January 2014) among APS-C Mid-Range DSLRs (Canon EOS 70D, Canon EOS 700D, Nikon D5300, Nikon D7100, Pentax K-3 and Pentax K-50).
Pentax K-500 is an entry-level sibling of K-50, sharing with it most features. The main differences between the two are the lack of multicolor body options (only black), no electronic level as Pentax K-30 and Pentax K-50 and missing weather sealing in K-500.