One-piece or single-piece toilets have the toilet-bowl and flush-tank merged without any joints. Two-piece toilets, also called couple-suites, have a separate toilet-bowl and flush-tank which are installed together using fittings.

The one-piece toilet does not have a gap between the tank and the toilet bowl, ensuring better hygiene and ease of cleaning.

Compared to one-piece toilets, two-piece couple suite toilets are more economical and easier to transport.