README shows two ways to use different kernel

[ssfrr]

The README says:

If you wish to use a specific Jupyter kernel, you may pass the kernel option. This enables you to use ob-ipython with languages other than Python. You need to have the Jupyter kernel installed and working before you can use this.

When mixing code from different languages you will need to make use of the session argument.

#+BEGIN_SRC ipython :session :kernel clojure
(+ 1 2)
#+END_SRC

But then right below that also says:

If you have other kernels installed, you should be able to evaluate blocks by providing jupyter-X as the language, where X is the language name recognised by jupyter. For example, you can do something like this:

#+BEGIN_SRC jupyter-R :results raw drawer
x <- 3
x
#+END_SRC

Which of these methods is the preferred way to use a non-python kernel?