I have the 180, it has a 9-pin cable, not a USB port. I believe in the series of Bernina's that goes from 150 to less than 200, the higher the number, the more features the machine offers, so the 180 would have more features than the 165. The 180 has a B&W screen.
A friend was going to sell her 155 and it doesn't have a needle threader. My 180 has a needle threader and a whole bunch of stitches and features that hers doesn't have.
One significant difference in the 165 and 180 is the width of the feed dogs. They are 9 mm in the 180 and I think 5 mm in the 165. I bought the machine to do stippling and embroidery with and the wider feed dogs are fine for either one (actually they're better for embroidery because you can do wider letters). However, when I have done 1/4" piecing, the wider feed dogs do seem to want to "eat" the fabric, so I do 1/4" piecing on my Janome.
I LOVE my Bernina for stippling! Hope this helps. :D