What is the difference beween 'after half an hour' and 'in half an hour?'

[falling slowly]

Dear tearchers.

The wall will be ready to paint _______________

1. after half an hour
2. in half an hour

Teacher says 2 is right.

but when googled, I saw many sentences using "after"

what is right? and what is the difference between them?

thank you in advance

[awatef]

No difference between them they both mean the same thing

[Clark]

Dear tearchers.

The wall will be ready to paint _______________

1. after half an hour
2. in half an hour

Teacher says 2 is right.

but when googled, I saw many sentences using "after"

what is right? and what is the difference between them?

thank you in advance

"In an hour" is just about time as such.
"After an hour (of smth)" is a period of time filled with some action/process/event etc.

I'll be ready in an hour.
After an hour of speaking you feel like having a break.