I have been working (present perfect continuous) and I have worked (present perfect)

Compare the use of the present perfect continuous and the present perfect:

PRESENT PERFECT CONTINUOUS: The visitors have been arriving since 5 o’clock. 

PRESENT PERFECT: All visitors have arrived — they are in the wedding hall. 

PRESENT PERFECT CONTINUOUS: I have been learning the English language for two years. 

PRESENT PERFECT: I have learned the English language for two years. I can now speak fluent English. 

PRESENT PERFECT CONTINUOUS: She has been driving for five years now. 

PRESENT PERFECT: She has driven all the way here without a break. She must be tired. 

We use both the present perfect continuous and the present perfect to talk about something that started in the past and which affects the situation that exists now. The difference is that the present perfect continuous focuses on the activity or event which may or may not be finished. The present perfect, however, focuses on the effect of the activity or event, or the fact that something has been achieved. 

Sometimes the difference between them is simply one of emphasis: 

I have been following their discussion with great interest. = (emphasizes the activity)

I've followed their discussions with great interest. = (emphasizes the result)

We can use either the present perfect continuous or the present perfect to talk about activities or events that are repeated again and again until now:

Ted  has been kicking a football against the wall all afternoon, (or ...has kicked...)

The public has been calling for her resignation for several weeks, (or ...has called...) 

However, if we mention the number of times the activity or event was repeated, we use the present perfect rather than the present perfect continuous:

I've seen her five times this week. 

He has played for the national team in 65 matches so far.

When we want to emphasize that a situation has changed over a period of time up to now, and may continue to change, we prefer the present perfect continuous to the present perfect:

The pollution problem has been getting worse over the last decade.

Sales have been increasing for some time. 

However, if we talk about a specific change over a period of time that ends now, particularly to focus on the result of this change, we use the present perfect:

Prices have decreased by 7%. {= in a period up to now)

The population has grown from 35 million in 1950 to 42 million today.