Both of these words refer to people who work at a company - but staff is always singular and uncountable - it describes the entire group of workers as one thing. Employees is plural and countable - it describes the collection of individual workers.
The entire staff was happy about the extra day off.
All the employees were happy about the extra day off.
Note that "staff" takes the singular verb was, and "employees" takes the plural verb were.
Whenever you use a specific number, use employees or staff members:
Terrifying Demons That Wont Let You Sleep At Night
In Slavic mythology the drekavac appears as a very scary looking demon that in reality is the ghost of an unbaptized childs soul. Its appearance varies depending on who sees it since it is so horrifying that few can stare at it long enough to give a proper description. The creepiest description so far is without a doubt the one where the drekavac appears in the form of an undead child who begs and calls for people passing near the cemetery to baptize it.
In later Slavic traditions the drekavac is connected with Christmas, specifically the twelve days of Christmas during which it is believed that when a drekavac appears in a childs form it usually announces someones death.