We can not positively identify a cultivar visually though we can sometimes make a guess. The history of the plant is very important and unfortunately, people often don't know it. However, you can read about the plant especially if they know it's a University release and narrow down your fruit ID to 2-3 cultivars based on size, color, fruiting time. etc. Here are some resources to help:

VIDEO: How to Identify Your Apple Tree https://youtu.be/1xFw1YmIu-E

U of M varietal releases: http://mnhardy.umn.edu/varieties/fruit/apples/all-apple-varieties

Extension Yard & Garden Fruits: https://extension.umn.edu/find-plants/fruit

Also, here is a nice discussion about identifying apple varieties. Though it is written about English varieties, all the principles are universal.

http://www.suttonelms.org.uk/apple55.html

If you want to pursue more conclusive testing, UC-Davis will accept samples for DNA fingerprinting. The cost is $345 per sample.

http://fpms.ucdavis.edu/IDTesting.html

http://fpms.ucdavis.edu/IDTesting.html