Inthree-dimensional space and below, the termssemiregular polytope anduniform polytope have identical meanings, because all uniformpolygons must beregular. However, since not alluniform polyhedra areregular, the number of semiregular polytopes in dimensions higher than three is much smaller than the number of uniform polytopes in the same number of dimensions.
The three convex semiregular4-polytopes are therectified 5-cell,snub 24-cell andrectified 600-cell. The only semiregular polytopes in higher dimensions are thek21 polytopes, where the rectified 5-cell is the special case ofk = 0. These were all listed by Gosset, but a proof of the completeness of this list was not published until the work ofMakarov (1988) for four dimensions, andBlind & Blind (1991) for higher dimensions.
Gosset's 4-polytopes (with his names in parentheses)
Makarov, P. V. (1988). "On the derivation of four-dimensional semi-regular polytopes". Voprosy Diskret. Geom.Mat. Issled. Akad. Nauk. Mold.103:139–150, 177.MR0958024.