I agree with what was said above.
The big difference for me was the flotation in the front that allows you to drive it hard (very hard) and not worry about pitchpoling. This is especially important if you have a heavier crew or more than 2 on the boat. It is bigger and more stable than the 16, not as sensitive to weight distribution. I have the wings and love them, they make sailing much more comfortable, drier and easy + more room on the boat, you can even sit on the wing at the dock and it is no issue. With 3 on board it is very comfortable. My crew likes to sleep on the leeward wing when the wind is not up. I sail on a lake so the daggerboards are not an issue, they do help the boat to point a little better than the 16.
Overall I used to sail both a 16, 18 with wings and many other small sailboats (available to me through the college sailing club) and I always chose the Hobie 18. When it came time for me to get back into sailing, I went for the 18 with wings and love it. The 16 has some advantages but the 18 is my choice