There are 3 deciduous oaks that you are likely to see in the wild. They are the English Oak, the Sessile Oak and the Turkey Oak. In winter you can’t identify them from a distance but if you look closely at their buds and old acorn cups you should be able to tell one from the other. All the photos shown in this post are taken from the Tree Guide UK app.
Oaks have clusters of buds at the end of each shoot.
The English Oak has buds that have fewer bud scales than those of the Sessile Oak.
These are the terminal buds of the English Oak. Each bud has a series of overlapping bud scales that protect the bud though the winter.
English Oak buds have fewer than 20 bud scales.
These are the buds of a Sessile Oak. These buds have more than 20 bud scales
This is the old acorn cup of an English Oak. You will often find them under the tree in winter. The acorn of the English Oak is on a long stalk, as shown here.
These are the old acorn cups of the Sessile Oak. These cups are not on a long stalk. They sit on the shoot, hence the name sessile.
The buds of the Turkey Oak are hidden by whiskers.
The acorns of the Turkey Oak are also whiskered. So you should always be able to identify the Turkey Oak by it whiskers.