The kimono sleeve is always created from the same piece of cloth as the body of the garment like a traditional Japanese kimono. The sleeve can be very short or full length, with a narrow or wide hem. Sometimes for a more fitted kimono sleeve, a gusset is added at the armpit.
The dolman sleeve has been trending for a few years now. Also known as a batwing sleeve, the dolman is characterized by a large armhole opening that dramatically narrows at the wrist. The armhole can extend as low as the waistline. The dolman sleeve is often, but not always, made from the same piece of fabric as the body of the garment.
For more about the history of the kimono sleeve check out these posts from Gertie and Coletterie.