What's the difference between"tell sb.sth." and "tell sb. about sth"??

Question

Answer

We use 'tell... about' to report statements: 
'I told you about losing my credit card, didn't I?' 

But tell someone to do something reports an order: 
'I told you to keep that card safe.' 


tell somebody something: to give information to somebody by speaking or writing: 
'He told everybody he won the prize.'

Answer

I told Jack about Jane.
I told Jack that Jane bought a new ring.
That is the difference.
Good night.