Essentially, the difference between the two is simply where the images are taken. The biggest variance is that indoor sessions are captured using set lighting and a backdrop or similar set-up. This is very limited to changes however, it is much more predictable and isn't dependent on the weather or time of day. A studio session can take place at either the photographer's studio or a rented space.  On-location photography means a session that doesn't take place in the studio. This can be either indoors or outside. An on-location indoor session usually occurs in spaces such as my client's house, venues, business offices and, barns. There are endless opportunities for outdoor on-location sessions including parks, conservation areas, family-owned properties, and urban areas too.