Similar to a dish piston, the goal of a Reverse Dome piston is to lower the compression ratio of your engine, making them great for boosted (supercharged, turbocharged) applications. They are designed in such a way as to match the profile and shape of most standard and aftermarket cylinder heads.
Flat top pistons are very similar in nature to stock pistons, running at medium compression ratios. Consequently, they work great in many applications and performance levels. Valve reliefs are designed with appropriate clearance to fit most types of standard and aftermarket heads.