They're the same thing. Jersey is a type of stitch and fabric type. It's very basic in terms of stitching. You can googlle it for a better definition. Jersey for tees is a high gauge knit. The type of cotton and how the cotton is prepared is the difference.
If it's combed or carded for example. Is the yarn ring spun? Is the Yarn a compact? If it's a 10's or 60's yarn. Is it a 10's single or are they adding a ply.
In short jersey is a type of fabric and a stitch use in the knitting world.