I concur with Sam Harris and this quote from him on christianity: "Christianity is a cult of human sacrifice."
So, yes, I also think all religions are cults.

In a cult there is a person at the top who knows it's all a scam. In a religion, that person is dead.

[atheist.ie]

Thought it would just show the image.. Oh well... It's a Joe Rogan Quote... A cult is bullshit... It's created by one person and that person knows it's bullshit... In a religion. That dude's dead.

The snarky response is that a cult is a religion that is too young and/or too small to have become commonly accepted and respected (that is, normalized).

Others try to identify it with crossing some ill-defined line of being too controlling of its adherent's personal lives. But the conservative / fundamentalist wings of any religion qualify for that.

Others suggest that the term must be used in the sense of "cult of personality", that it must have a revered, unquestioned founder / leader who is seen as almost godlike. But the lines are blurry there, too. Kim Jong Un certainly represents a state religion personality cult. So do many Eastern gurus and Western televangelists.

Still others, usually fundamentalists, define it via serious doctrinal "error". For example Christian fundamentalists identify Mormons and Jehovah's Witnesses as cults, given the Mormon's violation of sola scriptura (they recognize holy / inspired books other than the Bible) and the JW's denial of the Trinity and of hell (these are the major bones of contention, by far not ALL of them).

"Cult" is a pejorative term with very negative connotations. For most people it evokes Jonestown, the Branch Davidians in Waco, the Hare Krishna, the Moonies, etc. While I find all of those groups to be very unsavory, I prefer not to use labels that generate heat rather than accurately descriptive light -- so I avoid the term "cult" for the most part. Religion, to me, is religion at some basic level. Since to me most religion is based on the failed epistemology of religious faith (uncritical acceptance of asserted truth), it's not helpful to try to grade different religions as more or less acceptable or desirable in such vague ways that mean different things to different people. More meaningful distinctions like liberal vs fundamentalist / authoritarian, are better ways to have a nuanced understanding of religion.

I think the main difference is just the size of the following !

Not exactly. A Cult is generally considered to be a fixation around a particular individual such as the Moonies or the Charles Manson acolytes. The main religions are all theist and centre their worship on God or gods. In the case of Judaism, Christianity and Islam they are monotheist and all believe in one god. There are many sects and groupings of course amongst the Christian faith, such as Mormons and Jehova’s Witnesses, but they would not really be classed as cults either.