Obviously there are major differences if the pot roast is cooked uncovered in the oven. That aside, are there differences if it is covered?
Braising can happen in the oven or on the stove top, and covered or uncovered. Covering limits evaporation. Braising in the oven provides the convenience of keeping the stove top burners free, and provide a consistent radiant heat. This might be important if uncovered, as evaporating liquid could create an issue with burning on the stove top. Evaporation concentrates flavor. This can be an advantage or disadvantage depending on your desired outcome. Braises are typically low temp/long time cooks. While covering vs. not, might impact cook time, usually with a braise, I don't find the difference to be that significant.
The difference in taste should be minimal, if everything is done right. But for completeness, here a list of the advantages and disadvantages:
Advantages of the oven:
- if the piece of meat is large, you run less risk of under- or overcooked areas
- if you don't have enough collagen, the results will be less terrible than on stovetop
- you are not limited to narrow vessels
- one less hob occupied
Disadvantages of the oven:
- needs longer time
- uses more energy
- risk of burning yourself if you grip the handles
- your oven is occupied