In the classical theology of mainstream Christianity; God outside of us is 'transcendent' and God inside us is 'immanent' (in the sense that God is in all of creation) - so they are 'the same thing'. This seems to imply that if we have one, then we did not need the other - and that having both God-without and God-within is redundant.
Traditionally - from the early days of a church - this was interpreted to mean that God would come to the Christian primarily from outside; the revelation was interpreted by the church and given to the follower. Later, from the Reformation (with the Quakers as an extreme version); God-within was given primacy. But both extremes share the understanding that both inner and outer God are the same - because God is a unity.
However, the pluralistic theology which I believe holds that God inside us includes our own unique and eternal self - which has been, has existed, eternally - as well as that divinity we have from the creator as consequence of being a child of God. Whereas God outside does not have our-own self in it.
So God-without and God-within are distinct, and both are necessary*.
God-without is generic, and applies to all Men - indeed to all creation: this makes us a part of God's destiny and all of Men our brothers and sisters.
God-within is what makes each of us a child of God, and makes God a matter of concern to each of us individually and personally.
We need both God-within and God-without if God's creation is to be both universal and specific.
And therefore revelation has both external and internal aspects. There is a universal revelation and a personal revelation possible - and both are necessary.
In navigating our way through life - we need both inner and outer God. It is the meeting of inner and outer that defines our own path, distinct from the path of any and every other person - but equally God-given.
It is the interaction of God-within and God-without that enables Men to become gods: in other words enables Men to participate in creation. It is love - between each Man and God and between Men - that makes the interaction of internal and external divine sources an harmonious interaction; each a positive and mutually-reinforcing contribution to creation.
(This is one reason why love is fundamental to Christianity - love is the cohesion of creation.)
And it is the meeting of inner and outer - which differ - that is the basis of our participation in creation. When we became God's children, it became possible for us to join with God in the ongoing work of creation - precisely because we each bring something unique and distinctive and potentially valuable to creation.
God-within is unique, and yet also includes God as consequence of being a child of God; this is how we can make a contribution to the creation which was begun only by God; but continues with the participation of newly made gods.
These newly made gods were men and women always with some divine nature, but able to develop to become fully-divine in nature.
It is because men and women were not wholly made by God, but instead each have something eternal which existed before we were made children of God, that we are unique Beings, and able to become gods - of the same kind as our Heavenly Parents and Jesus Christ.
*(God is not, therefore, a unity. God is, in the first place, a Heavenly
Mother and Father; and later included Jesus who began as a Man and
became fully divine. Because of the work of Jesus, potentially all Men could become divine - although in practice not all Men make this choice.)
Note: the above is an interpretation of Mormon theology, which I have also discussed further in my mini-book Speculations of a Theoretical Mormon from five years ago.