Collie on collie poor relations

Hi everyone! We just adopted a little collie but my other border collie is not into the puppy at all. It’s only been a week but every time the pup tries to play my dog ignores her and sometimes snaps at her 😩.

She usually likes other dogs and is playful with them so it’s making me quite sad. I was hoping for advice or reassurance that things will get better. Here’s a photo of them looking like they’re friends!