Retool

The original Bumblebee toy has been retooled in major ways twice, first to accommodate a keychain (right) and second with a more show-accurate head.

A retool is a newer version of an existing Transformers toy which has had parts either added, removed, or resculpted. This can be as simple as changing a single part to provide stability or ease of transformation, or as complex as altering a large percentage of the toy's appearance or gimmickry.... In rare cases, extensive remolding even changes some aspects of a toy's transformation.

Some refer to retooling as remolding, though this is not necessarily accurate. This implies an entirely new mold is made for the toy, while sometimes the parts for both figures are produced on the same sprues. In the case of Universe Rumble and Inferno, the only difference was the head, and both were on the original mold sprues for Scrapmetal. Odds are, the unused Cobybot heads for the thousands of Scrapmetals released got recycled with all the other plastic that goes unused when parts sprues are cast.

One of the most well known retools is the G1 Ultra Magnus, appearing to be a simple repaint of G1 Optimus Prime.

From Teletraan I: The Transformers Wiki, a Wikia wiki.