hook_load vs. hook_node_load?
This paragraph in hook_node_load() docs page explains it in details:


  This hook is invoked during node loading, which is handled by entity_load(), via classes NodeController and DrupalDefaultEntityController. After the node information is read from the database or the entity cache, hook_load() is invoked on the node's content type module, then field_attach_load_revision() or field_attach_load() is called, then hook_entity_load() is invoked on all implementing modules, and finally hook_node_load() is invoked on all implementing modules.


Here's the breakdown, from first to last call:


entity_load()
hook_load()
field_attach_load_revision() or field_attach_load()
hook_entity_load()
hook_node_load()


What this means to you is that using a different hook you will be able to modify values earlier or later. This matters if you're overriding value from another module for example. Otherwise, I think it's safe to use either.