Reallocated vs Preallocated - What's the difference?

As verbs the difference between reallocated and preallocated

is that reallocated is past tense of reallocate while preallocated is past tense of preallocate.

(head)

(reallocate)

To change the user or purpose for which a resource is allocated.

:I want to reallocate some of my money from stocks to bonds. (I want to sell some of my stocks and use the proceeds to buy bonds to replace them.)

To allocate again.

:[Appending items one at a time is] still a better deal than concatenation, which reallocates every time.

(head)

(preallocate)

* pre-allocate

(preallocat)

To set aside before a need arises for a purpose