There are a few more changes than the ignition. (many of which parallel the changes from the Husky 266 to the 268). The case was changed to accomodate the single coil ignition. That change moved the front bolt hole for the top cover about a half inch, so new and older style covers do not swap back and forth. The new top cover was also taller in order to accept a taller muffler. Putting a newer muffler on an older saw results in the older top cover resting on it causing it to melt. The old low profile muffler is NLA from either Jonny or Husky, so hang on to any decent example you come accross. The II's are also a slightly darker red.
None of this is all that significant performance wise, it's just that if you've got a project going, you need to know what fits and what doesn't.