Quantum mechanics is a physical theory which is extremely non-intuitive. The equations have been very successful in predicting experimental results, but there have been a wide range of interpretations of what those equations mean.

Some of the most common interpretations are summarized here:

Interpretation Deterministic? Waveform real? One
Universe?
Avoids
hidden variables?
Local? Avoids
collapsing wavefunctions?
Copenhagen interpretation
(Waveform not real)
No No Yes Yes No Yes
Copenhagen interpretation
(Waveform real)
No Yes Yes Yes No No
Consistent Histories No No Yes Yes No Yes
Consciousness causes Collapse No Yes Yes Yes No No
Everett many-worlds interpretation Yes Yes No Yes* Yes Yes
Bohm interpretation Yes No Yes No No Yes
*Many Worlds has no hidden variables, except for the multiple worlds themselves.

Each interpretation has many variants. It is very difficult to get a precise definition of the Copenhagen Interpretation - in the table above, 2 variants of the Copenhagen Interpretation are shown - one that regards the waveform as being a tool for calculating probabilties only, and the other regards the waveform as an "element of reality".