"built-in" means that the oven is part of the same design as the components (kitchen counter, sink, etc.) that surround it.
"recessed" has to do with the position of the oven. If an oven is recessed, it doesn't stick out from the surrounding surface: it's either at the same level as the surrounding surface, or pushed back deeper than what surrounds it. Often, this implies that the oven was built-in (as part of the original design), but it doesn't necessarily imply this.
By way of comparison, in this photo, most of the lights you see on the ceiling would be called "recessed lighting".