what you are calling heresy? duh!
Originally introduced by Iraeneus (in his "Against Heresies" volumes), heresy was not necessary a pejorative term. It referred to differing theoretical schools of thought on various positions and viewpoints. It became more and more pejorative as the interanl and external onslaught against the Christian faith progressed in the early centuries.
Lexically, hairesis (heresy) is from haireo or haireomai; to choose, select, take up, elect. A form of religious worship, discipline, or opinion.
In contrast to schisma (schism), it is only theoretical. One can hold different views than the majority and remain in the same body, but that one is a heretic. But when he tears himself away (schizo), he becomes schismatic. Heresy it theoretically schismatic; schismaticism is practical heresy.
Since there are large modern movements that have literally torn themselves away from the Body and labeled themselves in various manners, it is practical heresy rather than merely theoretical heresy.
The 1054 East-West Schism was aptly named. The Reformation was an attempt at purging internal corruption that was heresy, so it was inverse (and the Latin Church was the culprit in both cases) with the intent of exposing the internal practical heresy that was schismatic.
The Latins ultimately refused Luther's priests, so they were once again in practical schism to what should have been an internal Reformation.
The splintering of Protestant denominations came about in various ways, and it would take a case by case examination to determine theoretical or practical heresy and assign them to whomever.