EDP or EDT comes up with a lot of fragrances, and Y is a common place to ask it. I pour both, so here is what separates them.
The Eau de Toilette. The one I have is the 2022 version, so if you remember an older bottle, treat this as its own wearing. A sparkly, clean citrus and ginger opening, then lavender and clary sage over cedar and vanilla. Fresher and softer than the Eau de Parfum, with the same overall shape.
The Eau de Parfum. Apple and ginger up top, sage and juniper in the middle, cedar and warm amber underneath. It fits almost anywhere you would wear it. You have smelled it before. It is everywhere for a reason.
The letters on the bottle tell you about concentration. They do not tell you which one you will like. The EDT is the brighter, lighter one, filed on the site for summer and spring. The EDP is warmer at the base and filed for spring.
If you are choosing blind, take a 2 ml of each and wear them on two similar days. That is one person's impression and not a universal read.
Y Eau de Toilette and Y Eau de Parfum are both here in 2, 5 and 10 ml, each poured from a 100 ml bottle. Which size to get goes through the sizes.