Hello Kim, and welcome to the Cafe and the would of engraving.
For many thing, straight lines or gentle curves #1 will work fine.
#2 will create less heel drag on tight curves and small scroll.
Both types of heel have been around and successfully used for many years.
I have used both types on almost everything. The only difference I could determine was if you go too deep with the conventional or #1 type you cannot come out of the cut. When using the number 2 type or parrallel heel it doesn't matter how deep you go. The graver won't dive on you. But the extra time involved in sharpening isn't worth the effort to me. Both cut around corners the same if you lean them some to the outside of the curve. In my opinion if you can't come out of the cut with the #1 type your cutting too deep. Most beginners tend t ocut too deep
#2. the shorter the heel, the better for tight curves. i never measured, just eyeballed. sam alfano advised not much wider than a human hair. btw, don't know how a bald guy used a hair as a guide. where did he get one ??
I engraved with a 90° #1 for 25 years.
I started with #2 when GRS introduced their EasyGraver fixture, which I wanted the speed and convenience of. I can engrave equally well with either geometry but as Roger pointed out, #2 is well suited for flare cuts.