These two prepositions have a very close meaning and sometimes can be used interchangeably. But be careful, there are special cases when doing that can cause an error in a sentence.
At first, let's look at the cases when we can use both above and over. It happens when the meaning of above is ‘higher than’. For example:
My mom loves to fly by airplanes. Most of all she likes to look at the porthole when the plane gets above/over the clouds.
It's amazing how that little dog could make a jump above/over my head!
We can also use both above and over to refer to temperatures in some contexts. For example:
The temperature got above/over 50 degrees.
Then, let's look at the sentences when we can NOT use above and over interchangeably.
We use above:
- to talk about things that have an upper level;
- when there is no physical contact between things we mention;
- to talk about temperatures in relation to zero.
The National Weather Service confirmed a waterspout appeared above Normandy Beach in Ocean County during Tuesday's thunderstorms. (nj.com)
The data above was compiled by Johns Hopkins University. (CNBC)
The temperature got 5 degrees above zero.
We use over in a more general meaning and prefer this preposition for numbers. Also, we use it in cases when there is a physical contact between things we mention.
It was raining heavily, so he put his coat over her.
Department of Health reports 58 new COVID-19 deaths, over 1,100 new cases. (WKBN.com)
Oil prices go negative — and Washington is paralyzed over what to do. (Politico)
Everyone over 18 was charged with robbery by sudden snatching without a weapon, battery and damage to property. (TCPalm)
The City of Everett is now requiring anyone over the age of 5 to wear a face covering when in public places. (CBS Boston)