Entity attachments are different than interdimensional parasites. Interdimensional parasites are instinctual based creatures, akin to the symbiotic parasites that live on our skin.

Entities that get attached may have volition or are being controlled by a being outside our EM (electromagnetic fields). Entities may have once been alive or exist with rudimentary and/or twisted intelligence. They are drawn to biological beings that produce a lot of light. They may be pernicious in their intent to stay attached. And entities are different from probes that may come from ETs.