Check the label on the rack at the wood shop
Not trying to be smart with that one, but I really get what you are asking.
Hard (Sugar) Maple has a (mean) density of about 44 lbs/cubic foot - soft (Red) about 38 lbs/cuft - but with a 10% allowable variance that gives you ranges of 39-48 (hard) and 34-42 (Red) - not conclusive if you measure weight.
You can usually dent Red with a finger nail, but you can sometimes dent Sugar.
Sugar normally has tighter rings - but again that depends on where it was grown.
Red sometimes has darker streaks and an overall darker appearance - (sometimes but not always).
Which leads me back to my first comment...