Einstein thinks that quantum mechanics is incomplete because it introduces probability into physics, just as you can only predict the probability of an event, but you can't give an accurate and definite prediction like Newtonian mechanics.

On the other hand, Einstein put forward the EPR thought experiment, which was later perfected by Bohm, and directly exposed a kind of over-distance (non-relativistic) effect embodied in quantum mechanics.

Bohr's point of view is that quantum mechanics is complete, and there is only one quantity that we can measure, and this quantity is real. However, the quantities abandoned in quantum mechanics, which only exist in classical mechanics, cannot be measured in the microscopic world, so these concepts are meaningless. Quantum mechanics has been able to explain the micro-world well and make quantitative calculations in line with the experimental results.