Definition 1.1 of Algebraic Theories says an algebraic theory is a small category $\mathcal{T}$ with finite products, and an algebra for theory $\mathcal{T}$ is a product preserving functor $A$ from $\mathcal{T}$ to $\text{Set}.$
My question is, how is this concept related to the idea of an algebra over an endofunctor or of an algebra over a monad ?
For example, I am wondering if there is a connection with some Eilenberg-Moore categories.