A B-tree could only be confused with a binary tree if it is binary with each node having at most 2 children. Wikipedia states this clearly, "a binary tree is a tree data structure in which each node has at most two children." The SQL Server documentation that references B-tree doesn't clearly state how many children a node can have, but I can tell you it is more than 2.

The Wikipedia reference to a B-tree as a generalized form of a binary tree is accurate. But it doesn't mean that a B-tree is a binary tree any more than saying a polygon is a generalized form of a rectangle means that a polygon is a rectangle.