Bitcoin is a virtual currency that exists only digitally and can be purchased only online whereas gold is a physical assests that you can touch and hold. The difference between is currency part . Bitcoin is more volatile as compared with gold. Bitcoin is referred to as a gold. Both have their own importance on their own.
with the introductions of bitcoin atms its now possible to buy bitcoin offline .
your right tho , we can differentiate them easily because one is more of a currecncy and that was bitcoin while the other is more of an investment .
bitcoin is bitcoin and gold is gold but what you mean is bitcoin is sometimes being called as a digital version of gold .