Identifying a Chemise is quite simple. The length of a Chemise usually falls above the knee and will be more form fitting than a Babydoll. Chemises will have spaghetti straps and often a hook & eye closure in the back. Like most lingerie types, Chemises are offered in any color of the rainbow, and with choice of fabrics, including laces, meshes, satins and silks, it's hard not to find the combination that feels right for you.
A type of Chemise known as a "Style Chemise" will have a looser, more comfortable fit. The "Sleepwear Chemise" has no fasteners and will typically be put on by slipping on over your head, very similar to the common slip.
You will often come across a "garter slip", which is a variation of the chemise with the addition of garter straps that can be removed or may be permanent.