Similar species: Balsam Fir (Abies balsamea) - needles are white underneath. Eastern Hemlock (Tsuga canadensis) - needles are white underneath. Mugo Pine (Pinus mugo) - needles are very different.
Yews are low-growing shrubs. Yew never grows into a tree form in the wild. However, there are ornamental types which do grow more upright, but these are unlikely to be found growing wild. This picture shows the typical overall form of a Yew. They have a sprawling, spreading form.
A closer view of Yew needles. Yew needles differ from Balsam Fir and Eastern Hemlock (Tsuga canadensis) in that Yew needles are green underneath (not shown here).
Please note that although a delicious tea can be made from both Balsam Fir and Eastern Hemlock needles, this is not the case with Yew needles. Since there is conflicting literature on whether or not one can make tea from Yew, it is probably best to not do so.
Note the flower buds on the underside of the twigs.