burn away—
1. continue to burn:
- The fire was still burning away cheerfully in the grate.
2. become less or be destroyed by burning:
- Half the oil in the lamp had burnt away.
burn out—
1. burn visibly:
- The lamp burned out in the darkness of the night.
2. stop burning because there is no more fuel:
- As the first rocket burns out, the second stage motor ignites.
3. (of an engine, etc.) stop working through overheating:
- The engine burned out because of a problem in the cooling system.
4. (usually Passive) be made hollow by fire:
- The building was burnt out and only the walls remained.
5. decrease; die down:
- The poet’s ability burned out before he was thirty.