Are they the same? and Why?

Only the 2nd one is a good choice.

Can you explain why please?

Because you wish to advertise that it is an ongoing accomplishment. Present perfect simple only speaks of past accomplishment here.

I really appreciate your help Mister Micawber.

"We have changed deserts into cities for 20 years"

" We have lived here for 20 years"

I beilive the last one is correct.

Aren't both of them an ongoing activity ? If not , please explain.

Thank you VERY MUCH for your time.

'We have been living here for 20 years' (present continuous) makes it clear that you are still living here. Also, 'live' is a stative verb while 'change' is a dynamic verb. Together, these considerations make 'we have changed deserts' the wrong choice.

look at these please,

"We have changed thousands of hectares of jungle into new rubber plantations since 1970"

"We have changed thousands of hectares of jungle into new rubber plantations for 20 years"

are these correct?

Thank you for your time

The grammar is correct, but they make poor advertising copy. They suggest that you no longer change jungle into rubber plantations.

(Which to me is a wonderful prospect, but no doubt your bosses want to continue detroying the jungle!)

It is truly an unfortunate topic to deal with.

So, I hope you have a bit more patience left for me.

When we say :

When we say " We have changed thousands of hectares of jungle into new rubber plantations since 1970" it means that we did the "changing" but not any more.-- It refers to past events; you may or may not be continuing to do so.

and when we say "We have been changing thousands of hectares of jungle into new rubber plantations since 1970" It means we did and still do

Mister Micawber, I just can't thank you enough.

Thank you