If you want to work a flat pattern in the round, you have to reverse the wrong side rows--knit the purls and purl the knits and work the stitches in reverse order.
When you knit in the round, you're always working on the right side--there are no wrong-side rows.
When you work flat, for example, you can imagine that the stitches are worked 1,2,3,4,5, etc on the rs rows, and 5,4,3,2,1 on the ws rows. All stitches in the round are worked 1,2,3,4,5. . .
So if you work stockinette, you knit every row. Garter stitch would require you to knit one row, purl one row. Seed stitch would still be k,p,k,p and you just purl the knits and knit the purls on the next row.
Most patterns worked in the round are written for in the round, though.