Made to measure suits can be a good option if you are having a hard time working with off the rack menswear. If you’ve got strange physical measurements (big shoulders, long legs, etc…), this might be the way to go.
I often would get made to measure and bespoke suits confused. There are some subtle differences but some people use the terms interchangeably. Bespoke is often more detailed with the measurements, as the suit is being custom made for you, usually by hand.
Bespoke tailors will usually take more detailed measurements and have a wider variety of cloths to choose from. Of course, this tends to be much more expensive. Think Savile Row in London. Its great if you can afford it, most most guys can’t. That’s where MTM comes in.
Both involve taking a series of measurements. Made to measure wear can be done at a suit shop or department store, any where suits are sold. They will then take those and apply it to the available suit fabric that you have selected. With made to measure, these suits are generally made at a factory and may have limited fabric choices. It may just be a set stock pattern they use for it. For example if you get a Zegna made to measure, you may have a selection of several fabric types.
As mentioned, many stores offer this service, and it can be a good way to get a suit that fits you well. The biggest key is the tailor who is doing the measurements. Ideally you want this person to be a dedicated tailor, not a salesperson with a measuring tape. If you have a poor measurement, you won’t know it until the suit comes back, and by then its too late.