Semigloss - less shiny than high gloss, and isn't as likely to show surface imperfections. Recommended for kitchen and bathroom walls, children's playroom, woodwork and trim. Eggshell - can be used in place of flat paints on wall surfaces, especially in halls, bathrooms and playrooms. Sometimes recommended in place of semigloss paints on trims for a less shiny appearance. Flat - for general use on walls and ceilings.
Flat paint can hide surface imperfections, but stain removal can be difficult.
Best suited for low traffic areas. Again, your local paint retailer can certainly recommend the type of gloss you'll need for your particular project.