There are several ways to transition from one floor to another. 1) Tuck cpt directly to the tile with no transition. 2) Use a product called a schluter strip (schluter.com) or blanke ceramic tile trims and profiles (blankecorp.com) - they are metal strips that are available in a variety of finishes, one side is laid under the last row of tiles and tuck the cpt to the other side (very clean finished look) 3) use a wooden threshold either a t-mold or a square nose (sometimes called a baby threshold) if you decide to use a t-mold make sure the cpt tackstrip is under the T to give it support to prevent cracking.