It is indeed a massive difference. Even Apr 15 to Apr 20 is a huge difference.
In 130 years of record (since 1891) Toledo has seen a 1"+ snowfall only 4 times on or after April 20.
4.0" Apr 23-24, 2005
4.0" May 9, 1923
2.0" Apr 21, 1922
1.3" May 6-7, 1989
In 140 years of record (since 1881) Detroit has seen a 1"+ snowfall only 8 times on or after April 20.
6.0" May 9, 1923
5.0" May 21-22, 1883
4.3" Apr 23-24, 2005
3.0" Apr 29, 1909
1.7" Apr 23-24, 1967
1.5" May 13, 1912
1.2" Apr 20, 1947
1.0" Apr 22, 1911
*Note. per newspaper reports Toledo saw 3" during the unprecedented May 21/22 1883 storm, but records did not yet exist.