You may need to use url encoding to match the string in the API fields. They'll be converted to their %## values (depends on the character). This is documented (somewhat) in the API documentation:
Name of this entity, unique relative to its parent.
Any / (slash), \ (backslash), character used in this name element will be escaped. Similarly, any % (percent) character used in this name element will be escaped, unless it is used to start an escape sequence. A slash is escaped as %2F or %2f. A backslash is escaped as %5C or %5c, and a percent is escaped as %25.
I usually pass the strings through a URL encoding library for comparison. Some of the SDK kits will do the URL encode and decode for you automatically. You can also look at the MOB, see if this provides better detail on the actual display name content.