The -eq (equal to) and -ne (not equal to) operators perform exact (and, by default, case insensitive) comparisons. In the example below, the following returns true:
1 -eq 1 'string' -eq 'string' [char]'a' -eq 'A' $true -eq 1 $false -eq 0
Similarly, -ne (not equal) will return true for each of the following:
20 -ne 100 'this' -ne 'that' $false -ne 'false'
The last example compares $false, the Boolean, with a string containing the word false. PowerShell will attempt to convert the word, but as the word is not an empty string, the result will be true.