**Core Concept**
High mannose and complex glycoproteins are two types of glycoproteins that differ in their carbohydrate composition. High mannose glycoproteins contain only mannose residues attached to the asparagine residue of the protein backbone, whereas complex glycoproteins have a more complex structure with both mannose and N-acetylglucosamine (GlcNAc) residues attached.

**Why the Correct Answer is Right**
The difference between high mannose and complex glycoproteins lies in their biosynthesis pathway. High mannose glycoproteins are formed through the action of the enzyme N-glycosyltransferase, which attaches a high mannose oligosaccharide to the asparagine residue of the protein. In contrast, complex glycoproteins are formed through the action of the enzyme N-acetylglucosaminyltransferase, which adds GlcNAc residues to the high mannose oligosaccharide, resulting in a more complex structure.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because high mannose glycoproteins do not contain any N-acetylglucosamine residues.
**Option B:** This option is incorrect because complex glycoproteins do not have the same structure as high mannose glycoproteins, they have a more complex carbohydrate composition.
**Option C:** This option is incorrect because the difference between high mannose and complex glycoproteins is not related to their function or location in the cell.

**Clinical Pearl / High-Yield Fact**
It's essential to remember that the difference between high mannose and complex glycoproteins is not just a theoretical concept, but has significant implications for the function and regulation of glycoproteins in various biological processes.

**Correct Answer: A. High mannose glycoproteins contain only mannose residues, whereas complex glycoproteins have both mannose and N-acetylglucosamine residues.**