Coverall or Overall- Definitions of Clothing Terms presented by Apparel Search

Boilersuit

This is sometimes called a coverall. In American English, it is nearly always referred to as coveralls. It is a one-piece garment with full-length sleeves and legs like a jumpsuit, but usually less tight-fitting and worn as protective clothing over "street" clothes at work. Its main feature is that it has no gap between jacket and trousers and no loose jacket tails. It often has a long thin pocket down the outside of the right thigh to hold long tools. It usually has a front fastening extending the whole length of the front of the body up to the throat, with no lapels. This fastening can be:

Buttons.

A zipper.

Velcro, as nowadays in the British Royal Air Force (RAF).

Snap fasteners or press-studs.

They are often issued by factories to their workmen, with the firm's badge on.
The French police unit called CRS use boilersuits as uniforms.
A dark blue coverall is the current working uniform of the U.S. Navy, with the owner's name and "U.S. Navy" on the chest, and rank insignia on the collar points.

Military overalls

In the British Army, male Officers' mess dress in most regiments includes a pair of very tight wool trousers which extend above the waist and are worn with braces. These are properly known as "overalls". Essentially all regular officers have their mess dress tailored for them, along with their other formal uniform (the Sandhurst timetable includes time for this, and an allowance is paid for the cost) but donning the overalls for the first few times can still sometimes be difficult. Stories are told of officers being fitted into their trousers by two friends lifting them into the air by the waistband and bouncing, though in truth this is rare and more likely the result of weight gain some years after finishing training (most military tailors allow plenty of room to "let out" clothing over the years). Certainly it may be difficult to bend over in a new pair of overalls, but the wool soon stretches and becomes more comfortable.