Selecting difference between two tables returns different number of results than counts of same two tables

I'm using SQL Server and when I run

SELECT * FROM TABLE1 EXCEPT SELECT * FROM TABLE2

it returns 1610 entries. When I query

`
SELECT COUNT(*) FROM TABLE1 
SELECT COUNT(*) FROM TABLE2

` I get 6399 and 4583, the difference of which is 1546, not 1610 as I would expect from the first query. What could be causing this discrepancy between the number of results returned and the difference of the individual table counts?