There are a few distinct sets of pantheism. These different kinds of pantheism don’t tend to distinguish themselves from each other with distinct terminology, so let me just state the ones I’ve identified with some proposed terms so we may distinguish better between them:
1. Divine pantheism — There are those who say the universe is identical with divinity, or that all that exists is God. As far as I’m concerned this is still a distinctly theistic sentiment. The distinction however is that this God would not be personal nor anthropomorphic, which in my opinion detracts from the notion of a God anyway. I consider divine pantheism to be the most sophisticated version of a belief in God and just about the only sense of God that is to be taken seriously to some extent.
2. Placeholder pantheism — There are those who equate the universe with God and make no further attempt at explaining why. This seems to be more of an emotional rather than a rational perspective, as one has to wonder what kind of distinction is even made here. They replace one word with another one but it seems to have no bearing on what they actually believe. This could be seen as a variation on point 1, but with a more neutral sentiment. You might say secular, but that term is somewhat dubious in this context.
3. Natural pantheism — There are those who equate the universe with God as an indication of a component that could in some sense be regarded as God, but doesn’t really fit any of the definitions.
4. Spiritual pantheism — There are those who frame the universe as God as an indication of their reverence and awe in regard to the universe. This negates the notion that atheists can experience the same sense of awe, but I consider it a reasonable definition, as atheism indicates what you don’t believe and not what you do believe. While pantheism in this sense doesn’t explicitly state what is believed, it’s an indication of a certain sentiment that may set the pantheist apart from the atheist, even if what they believe in rough terms amounts to the same. This, by the way, is considered to be Spinoza’s pantheism, which Einstein seemed to have adapted as well.
5. Scientific pantheism — There are those who are basically atheists but object to that term because it’s a way to define part of your position in relation to theism, and doesn’t explicitly say anything about what you do believe. This is sometimes referred to as scientific pantheism, so this isn’t a term I made up. What distinguishes scientific pantheism from natural pantheism is that the scientific pantheist seems to be more prone to follow what is knowable, while the natural pantheist makes considerations of unknowable aspects of nature.
Pantheism is the belief God and the universe can be equated; that God is the universe. This is different from panentheism (also called monistic monotheism), where all is in God; it says the divine interpenetrates all aspects of the universe and transcends it. So in panentheism the divine is separate, whereas in pantheism the universe itself could be defined as the divine. It’s often no actual divinity however, but a spiritual reverence, or awe. You could rightfully call it the sublime, but I suppose that would apply to panentheism equally.
Furthermore, just as there is panentheism relating to pantheism, there is also panendeism relating to deism. The prefix ‘pan’ indicates ‘all’ (where ‘pantheism’ denotes that ‘all is God’), whereas ‘panen’ as far as I can gather means ‘all in’ (where ‘panentheism’ denotes that ‘all in God’). So the difference between pantheism and panentheism is that one denotes that all IS God, whereas the other denotes that all is IN God; one equates all with God, whereas the other indicates we are part of God.