Sure-Surely | Commonly Confused Words

Sure

/ʃʊə/

Being certain or confident about something without a doubt.

Old Mrs Smith did not invite you, I am sure."But if Lyon calls you, please tell him." "Sure, sure.Clients like the two of you I sure need!"

/ˈʃɔːli/

Certainly or without doubt

'Surely that must content you!Surely the idea is too fantastic."Surely there is enough evidence against him.'

Sure is often used as a straightforward confirmation or affirmation, like saying yes.
Surely is typically used to express confidence or certainty about something.
Remember that surely often adds an emphasis on the speaker's opinion or expectation.