Toilets come in one- or two-piece construction. Two-piece toilets employ a separate tank and bowl. One-piece toilets, also called "low profile," merge the tank and bowl into a single unit. A two-piece model will cost less, but a one-piece toilet is easier to clean because it does not have the crevice between the tank and the bowl.
Before shopping, be sure to measure the "rough-in," or the distance from the wall to the center of the toilet drain. Common "rough-in" are 300mm, 250mm and 200mm. In some cases, you might encounter 450mm or to the extend of 540mm "rough-in". Therefore, it is advisable to know the "rough-in" of your existing toilet bowl before going shopping for one.

