As there are a lot of mis-labeled items for sale on EBAY, a need for definitions is in order here. You can not have a "decal" and a "sticker" as ONE item.
A DECAL is customarily defined as a thin film printed on paper that is detached from the paper by soaking in water, then sliding the film onto the item receiving it.
This is why it is called a "water-slide DECAL."
A TRANSFER, often called a "SPIRIT transfer," is a special item printed in REVERSE on paper. If you look at it before applying it, you see the back side of it. It is applied by a special technique, using the special varnish used to apply gold leaf. When it is stuck in place, the paper is then wetted and peeled off, leaving the image visible, proper-side-up.
A STICKER is just that: a gummed-back label. This is what the red BSA logo was on the tanks of the 441 Victor Specials. The shortcoming of this item is that over time, the sticker SHRINKS, leaving a gummy dirt-collecting black ring around the sticker. I know this problem from experience.
ALSO, "stickers" rarely conform properly to curved surfaces.
SO: be careful what you order. Ask the seller to define what he is really marketing before you buy it.