One comparison lives here: how a rigid bangle and a chain bracelet differ on an Orlando wrist. Heat, stacking, and how you get the piece on.
A closed rigid bangle has to pass the hand. You compress the thumb, angle the piece over the knuckles, and let it drop to the wrist bone. If it will not clear the knuckles, it will not go on. An open cuff slides from the side. A chain opens at the clasp. It never has to pass the knuckles as a closed ring of metal.
A common U.S. jewelry-trade convention, published in wholesale size charts such as the Rings & Things bracelet size chart, is to measure wrist circumference with a flexible tape or a strip of paper, then add ease for a chain, and read a slip-on bangle as inner diameter because it has to pass the hand. ISO/DIS 25212 is a draft attempt to define bracelet size. It is in enquiry, not a finished retail law on this shop.
National Weather Service treats heat index as the temperature the body feels once humidity is counted, and reminds people that published values are for shade. Summer along I-4 is not shade all day. Wrists swell. A clasp that closed at a hotel breakfast can feel mean at three o'clock on International Drive.
Bangle versus chain is the full compare. Measure first on how to measure a wrist. Gear to try is on Wrist kits.
Get this a rigid bangle if it has to pass the knuckles. Get this a chain if the clasp is how it opens.
Open cuffs slide from the side and never have to pass the knuckles as a closed ring. Stacking a rigid bangle with a chain is a second sitting. Heat index in shade is not the same as three o'clock on International Drive. If the clasp that closed at breakfast feels mean at three, that is swell, not a bad buy. Measure again after the walk, or open the cuff. The nested lecture is Bangle vs chain.