In English, continuous tenses do not exist. There are continuous, or progressive forms of verbs, but NOT continuous tenses. (While in the Romance languages there are what is called imperfect tenses, even these are translated as English progressive forms.)
So, concerning English grammar, there are only six tenses:
- simple present
- simple past
- present perfect
- future perfect
- past perfect
There are three forms of these tenses: Basic, progressive, and emphatic. Of course, each of the six tenses can be put into the Progressive (continuous, if you will) form. Here are examples to demonstrate the difference.
BASIC FORM PROGRESSIVE (uses to be in the tenses)
1. Present tense
I see I am seeing
2. Future tense
I will see I will be seeing
3. Past tense
I saw I was seeing
4. Present Perfect tense
I have seen I have been seeing
5. Future Perfect tense
I will have seen I will have been seeing
6. Past Perfect tense
I had seen I had been seeing
The Basic Perfect forms of verbs are used when an action has a definite beginning and an end (DURATION). In fact, the word perfect means completed in Latin.
For instance, I had seen the movie before, but I watched it anyway. "had seen" is an action completed in the past before the person watched the movie. [past perfect tense]
The Progressive Forms are used to express continuous actions in some tense as contrasted to actions often begun and ended at more definite times.
For instance, I was watching the movie when I fell asleep.
(The person was in the act of watching a film when he fell asleep)
Understand, now, that the Progressive forms can be in any tense. Thus, they can be in all the 3 perfect tenses as well as the 3 simple tenses:
- I have worked - Present Perfect Tense [basic form]
- I have been working - Present Perfect Progressive form
- I had worked - Past Perfect Tense [basic form]
- I had been working - Past Perfect Progressive form
- I will have worked - Future Perfect [basic form]
- I will have been working - Future Perfect Progressive form
Thus, there is no difference between tenses, only forms.
The perfect tenses of the Basic Form use have, has, had, or will have + the past participle.
With the Progressive Form of the Perfect tenses the helping verbs have been, has been, had been, will have been + the present participle are used.