A distinction between copies, versions, and variants is at work here.

It can include the optional tag to differentiate between different variants.

It has a neutralized and flat intonation which serves to moderate between variants.

However, the actual specifics between variants is vague.

As with the M28 series, the specifics between variants of the M97 are vague.

The evidence for interbreeding between modern humans and archaic variants has involved a bit of asymmetry.

An association between genetic variants in apoptotic genes and prostate cancer risk has been proposed.

The biggest differences were between variants modified for non-bomber missions.

Later we used those backpacks as a way to differentiate between variants, and ultimately a fun way to blow them apart.

Many online catalogs allow links between several variants of an author's name.