(The words grade and type are used interchangeably, they mean the same thing.)
There are multiple acne scales out there. In order to explain well and match products to acne type (or grade) I use the one by Dr. James E. Fulton Dr. M.D., Ph.D but I modify it a bit. In his scale there are 4 types or grades of acne. For each grade a person could have a little of that grade (type) or a lot of that grade. This system qualifies but does not quantify and so one grade is often not any better or any worse than the other.
Grade I acne: Pustules
Red, pus filled heads, some inflammation
Grade II acne: Comedones
black heads (open comedones) and white heads (closed comedones). Closed comedones are flesh colored with no or little redness. They often present with tiny little bumps all over the acne area. When extracted they often produce a small little hard 'core' like a small piece of dry rice. Closed comedones can be very stubborn to get rid of because there often is no hole or opening for which it can come out. Facials from an Esthetican experienced in extractions, are very helpful for this kind of acne. 
Grade III acne:
A mix of grade I, II and IV.
This client has a couple pus filled heads (grade I) and raised red bumps pustules (grade I), blackheads (grade II), red deep spots that are purplish and cystic (grade IV).
Grade IV acne: Cystic acne
Larger, raised, inflamed and hard feeling bumps with no obvious pus in them. These pimples are tender to the touch and can be quite large (though not always). In the cover photo for this blog she has a bit of cystic acne particularly on her chin.
In this photo most of this acne is cystic and along his jaw is very cystic.
This 5th grade I have come up with on my own. For years I would be unsure when I would see acne like this because it would look rashy and also look a bit like rosacea. So I have named it 'rashy acne".
Grade V acne: Rashy acne
Red that is not very demarcated by the pimple, instead it is blotches of red. And usually a few small papules with no or little pus. This can also very much look like acne rosacea so an experienced dermatologist or esthetician is helpful. One way to test if the area is acne or rosacea is to use 10% benzoyl peroxide on it. If it quickly starts to diminish is it acne. If after 10 days there is no change, it might be rosacea. 
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