Your body can't certainly tell the difference between glucose and fructose, but that's not what we are talking about. HFCS is typically either 42% or 55% fructose, which is very similar to sucrose (50% fructose).
If HFCS is problematic, white sugar is problematic in exactly the same way.
If HFCS is problematic, white sugar is problematic in exactly the same way.