There is no standard sizing for clothing as measurements are not the same across different brands and manufacturers.
Sizing can also differ between styles of the same label.
Each product will have a product description or a sizing chart to inform you of how a specific item fits.
Tight compressive fit, generally runs a size smaller then actual size.
Body slimming fit, thats generally true to size. (not compressive)
Comfortable professional fit, neither slim or oversized.