Adding on to what others have said, this is very non-straightforward.
As others mention, the failure criteria for a vacuum vessel and a pressurized vessel is quite different. There is one very large factor that no one seems to have mentioned yet.
When the spherical vessel is under a vacuum, it develops compression, and if it's a ductile material, it is susceptible to buckling. This becomes more an issue as the vessel walls become thinner relative to the vessel radius.
This is a completely different failure mode than tensile failure, and due to the nature of buckling, it can happen at a relatively lower compressive stress than an equal strength material would fail at tensile stress.
As others mention, with a vacuum you can only reach some maximum pressure difference, then your vacuum is perfect and you will have the maximum pressure difference. So in the case of waiting, the vacuum vessel may reach a maximum before failure, while the pressure vessel could keep increasing in pressure over time and would eventually fail.
If you were to lay out these ideal conditions:
- Both pressure differentials can increase indefinitely over time, one internally pressurized and the other externally pressurized;
- The material of each vessel is equally strong in tension and compression
I would expect the externally pressurized vessel to fail first more than the internally pressurized, because it has another failure mode that can occur below the typical failure stress of the material (depending on the thickness of the vessel walls).
Basically, tensile stress in the vessel provides negative feedback loop against failure, but compressive stress creates an instability where a small deformation can cause a positive feedback loop which leads to failure.
Also, the vacuum vessel might just crumple up depending on what it's made of, while the pressure vessel would be more like an actual explosion, basically regardless of what it's made of.