Many people use the terms toilet and commode interchangeably to describe the porcelain fixture located in a bathroom, and in one sense, both words describe essentially the same thing. One guest might ask for directions to the commode, while another might ask for the nearest toilet, and it is highly unlikely the host would only recognize one or the other. There are actually some differences between the two in the strictest sense, however.
A commode could also refer to a low-lying set of drawers, or a portable washstand with a cupboard hidden beneath the counter top. The definition of that most closely matches this discussion is a boxy structure that conceals and supports a seat over a removable chamberpot or bedpan. The key idea is portability: a commode is not connected to water or sewer lines, but serves more as a privacy chamber for users on the move, so to speak. It would find the user, not the other way around.
A toilet, on the other hand, is considered a permanent plumbing fixture. The porcelain bowl and tank attached to the floor of a bathroom, loo, or water closet can always be called a toilet. Although the term toilette can also refer to a woman's vanity or dressing table, this derivative refers solely to a water-filled fixture used for waste elimination. In the strictest sense, a bedpan or portable toilet seat with an attached dry receptacle would be a commode, while the water-flushed bowl and tank in the bathroom would be a toilet.
It is not unusual for these terms to be used interchangeably as different cultures begin to blend. Asking for the nearest bathroom in Great Britain, for example, may lead to some bemused looks, because they refer to that destination as the loo or water closet or WC. In certain Asian countries, there is no such fixture as a toilet, and users must squat over a designated opening in the floor to conduct their business. A separate cleansing fixture known as a bidet may deliver a jolt of clean water to users in some European locations.
In short, the only real difference between the two devices is portability, although few people alive today can remember a time when a portable commode would have been used in place of a flush toilet in a modern home.