Question: Is Atenism sun worship?

No. Aten is the One God of the Universe. Transcendent, Omnipotent, Omniscient, Omnipresent. Aten is beyond the bounds of human conception or understanding on any level. The only way in which humanity can even come close to a basic understanding of Aten is through symbolic representation. The image of the sun above our world is not just a sun but it represents life and sustenance. All life on our planet is sustained by the life giving rays of the sun and without the sun, life on this planet would cease to exist. But this is a symbol for the life giving power and care in which Aten gives all life on this world, it does not mean Aten is the sun. If this were so, we would have to ask, why only this sun? and not the countless other suns in the universe, what about the other worlds in the Omniverse (the collection of all universes and planes of reality), doesn't Aten watch over them as well? The answer is "Of course". Aten creates and sustains all things. It is that, for us, we are centered on life in the here and now. Aten is with us always and sustains us in each and every moment.

Whether it be the physical sun in the sky, or an artistic representation of the sun and the life giving rays, these are gifts given to humanity so that we may try to comprehend that which is incomprehensible.

Sun worship, as in viewing the physical orb of the sun as a sentient god would be paganism just like if a person were to bestow godhood to the moon, or a planets or a cloud, a mountain, a rock, tree or shrub.