Stratosphere-Atmosphere | Commonly Confused Words

Stratosphere

/ˈstratəˌsfɪə/

A layer of Earth's atmosphere above the troposphere where airplanes often fly

The plane climbed swiftly into the stratosphere.Balloon flights often reach the lower stratosphere.Stars shone brilliantly in the clear stratosphere.

This word has no synonyms

/ˈætməsfɪə/

The layer of gases surrounding a planet, especially the Earth.

The restaurant had a friendly atmosphere.The atmosphere during the concert was electric.

This word has no antonyms

The stratosphere is a layer of the atmosphere, so all stratospheres are atmospheres, but not all atmospheres are stratospheres.
Remember that strato- refers to layers, as the stratosphere is one of the layered regions of the atmosphere.
The atmosphere is the entire gaseous envelope surrounding Earth, while the stratosphere is a specific region within it.
Atmosphere starts with A which can stand for All, indicating it's the entire gaseous system around Earth.
Stratosphere is situated above the troposphere, which might help you remember it's not the lowest part of the atmosphere.