:salamext:
The arabic word 'jannah/jannat' actually means 'garden.'
And the english word 'heaven' actually means the seven heavens/skies above us. So paradise, and heaven are two totally different things.
The only reason the translations refer to jannah as paradise is to make it easier to understand.
A good example of the definition of jannah in the Qur'an is:
Surah Buruj (85:11)
For those who believe and do righteous deeds, will be
Gardens; beneath which rivers flow: That is the great Salvation, (the fulfilment of all desires),
Inna allatheena amanoowaAAamiloo alssalihati lahum
jannatuntajree min tahtiha al-anharu thalikaalfawzu alkabeeru.
..&
Allaah Almighty knows best.
:wasalamex
PS. Thread Moved to Arabic Section.