Used on all 1984 releases and 1984 releases only. This means most pressings of '82/83 releases carrying this label should have been released in 1984.
It seems that Slayer "Show No Mercy" and "Haunting The Chapel" the 1984 editions (silver label) were sold in 1987 with the sleeves of the 1987 Restless edition, with barcode + Restless logo, on the back of the cover.
The vinyls with "Silver Label" might been an "old/over stock" which have been distributed in new sleeves. in 1987.?
Used on most releases from 1988 to the very last original MB vinyl release in early 1990 . This means that all pressings before 1988 with this logo should be released in 1988 or later.
Colorwise these tend to vary as with the old versions, this may be manufacturing variations or possibly the result of aging.
There's some other versions as well, but they mostly apply to co-op releases with other labels. Note that some of these designes were borrowed by labels like; Roadrunner, Enigma Canada, and the UK "Metal Blade Z" branche, etc. These versions are not proper "Metal Blade Records" originals.
Here are examples.