Question: Is there a difference when the adverbs '*always, continually,forever,etc..*' are used with past simple and past progressive?

For example :

1. He **always/ continually** worked there.
2. He was **always/ continually** working there.

(What is the difference between the above two sentences?)

Answer: 
Let's say that a colleague mistakenly believes that Joe is a new hire. We might say:

*Joe has always worked here.*

to mean nothing more than the fact that Joe is not a new employee. He has been here for some while.

If we want to say that Joe never slacked off when he was working at Acme Widgets, but always took his job seriously and gave it his best effort:

*Joe was always working when he was at Acme Widgets.*
Sometimes, we use the past continuous as an alternative to the past simple for repeated or routine actions, with a little difference in meaning.

He always/continually worked there.

He was always/continually working there.

The first sentence literally implies that he always worked there, whereas, the second sentence does not literally mean so. It conveys the sense that he appeared to be always working there. In other words, it implies that he was seen to be working there very often.