The difference between stained concrete and sealer stained concrete is basically coverage. If you like your concrete "rustic" then stain may be for you. It enhances the discrepancies in a beautiful way. If you want your concrete to look more "uniform" and all the same color then sealer stain is for you. Sealer stain can cover the majority of concrete discrepancies.
Below you will see a patio before and after that we color corrected with a sealer stain.