The bottom chevron is the traditional one, asymmetrical, but with a more open YO. The top one uses a modified bunny ear decrease with a yarn over inserted between the two halves. This makes for better symmetry, but a less open YO at the bottom of the V. See the blog entry for instructions.
How to Join in the Round Invisibly To join in the round invisibly, cast on one more stitch than your pattern calls for. Then, when you’re ready to join in the round, slip this extra stitch to the left needle. Using the working yarn and the yarn tail held together, knit the first two stitches together. Now drop the tail and knit as you normally would.