[Flask] add_template_global vs context_processor

[Corey Boyle]

Does anyone know the difference between add_template_global and
context_processor?

I've used the template_global decorator to make a function available
in my templates, but I would also like to make a particular variable
available also.

I seems like they both do similar things, but I don't know if there's
something I am missing. Performance difference perhaps?