What is an attachment?
An attachment is the product that atomizers are screwed into, which in turn is then screwed unto the battery.
What is an atomizer?
An atomizer is the name of the consumable part that is inserted in an attachment.
Atomizers are the most important part of an attachment, but these two terms are not interchangeable.
Example: SOURCE orb 4 attachment with its 4 included atomizers on the right.