Weird, I haven’t noticed the new notes. There are the normal notes, overdrive notes, and hammer-on notes. Are they normal, white, or a bit smaller? If normal, they do nothing. If white, if you play them all perfectly you get more overdrive power. If a bit smaller and funky looking, they are hammer-on notes.
With the hammer-on notes, as long as you hit the first normal looking note, you don’t have to strum to play the hammer-on. You just have to hit the right color key. Of course, you can also strum it. Our general strategy is to try to hit every other one with a strum so that in case we miss one it won’t be a disaster.
All of those were in Rock Band 1 though, so unless you give a better description or link to a picture, I’m not sure my answer is helpful.