Avengers: Infinity War - Official Infinity Stone Powers Revealed (And What They Mean)

4. The Reality Stone

Power: Bend reality to your will

Item: Aether

Meaning:

The Reality Stone might essentially look like the weakest of all of the Stones by the MCU's definition since it appears to be no more than a conjurer's trick that allows the user to change reality temporarily, but it's very much a permanent deal, really.

Curiously, the Reality Stone must not be able to kill anything, despite the ability to change reality, or Thanos could have simply used it to change the universe fundamentally to have half of existence removed. It must be down to the need to use the other Stones to boost its powers onto a larger scale.

Difference To Comics:

In the comics, the Reality Stone is basically a genie as it gives the user the ability to fulfil their every wish, even if the wish is in direct contradiction with scientific laws. Which means Thanos COULD have used it to enact his plan, which suggests the MCU version is indeed subtly different. Specifically, the Stone allows the user to conjure any Alternate Reality they can imagine, which is mostly the same.