Generally speaking, recumbent bikes will be easier to use, especially for a longer duration, since you can comfortably sit down with full support. Further, even though they are stationary bikes, the recumbent bike still requires less skill to balance. There is just about 0 chance of falling off a recumbent bike.

Perhaps the most obvious difference is their positioning: recumbent bikes allow you to ride in a reclined position, while upright bikes require you to remain sitting upright throughout your workout. While recumbent bikes tend to be more comfortable and easier on the joints than upright bikes, they also offer a lower-intensity workout.

Both upright and recumbent bikes are designed to provide aerobic exercise that can help elevate the heart-rate, work the muscles, and burn calories when used correctly. As a general rule, however, a recumbent bike is likely to burn slightly less calories given the same level of perceived exertion than an upright bike.