If $A$ is a right $R$-module and $B$ is a left $R$-module, then the tensor product $A\otimes_R B$ is an object $X$ with a map $\theta:A\times B\rightarrow X$ such that $\theta$ is $R$-bilinear and $\theta(ar,b)=\theta(a,rb)$ for all $a\in A, b\in B, r\in R$; further the pair $(X,\theta)$ has following universal property. If $X'$ is an object and $\theta':A\times B\rightarrow X'$ is $R$-bilinear map with $\theta'(ar,b)=\theta'(a,rb)$ then there is unique $g:X\rightarrow X'$ such that $\theta\circ g=\theta'$.
In some books, the tensor product $A\otimes_R B$ is defined to be an abelian group $X$ with map $\theta$ satisfying universal properties as stated above. Whereas in some books, it is defined to be an $R$-module $X$ with a map $\theta:A\times B\rightarrow X$ satisfying above universal properties.
What is appropriate choice for tensor product, as module or just as abelian group?
If we accept it as abelian group, then we can give it a left $R$-module structure or right $R$-module structure; so it seems to me that it should considered as abelian group only (together with map $\theta$).
Whereas, the places, where the tensor product is defined to be a module, they do not mention whether it is left $R$-module or right $R$-module.
For definition of tensor product, we need to take one left $R$-module and one right $R$-module; so we can not define tensor product to be universal object within some category of left $R$-modules or within category of some right $R$-modules.
In above write-up, $\theta$ can be said to be balanced map; and tensor product is defined to be an object with a balanced map, satisfying universal property.
But my question is concerned about what the object there should be; whether it should be just abelian group of $R$-modules?