Also, the smell of the yellow wilty basil plants aren't as strong compared to the green, healthier ones

Are they getting the same amount of light and water? Any differences in the growing medium?

Looks like a different variety of basil to me...

That was my first thought too.

Maybe try changing out your potting mix? How long have you had the plant?

Downy mildew is a disease that's affecting basil plants right now.