Hcfyk

Does anyone here know the difference between unorganized and disorganized?

As far as I know, disorganized refers to something that was once organized and now isn't, and unorganized refers to something that lacks organization from the start.
Is that correct?

You could certainly attempt to construct two different usages along the lines you suggest but they would pass most native speakers by.

Consider the very strong case for regarding 'disinterested' and 'uninterested' as having very, and usefully, distinct meanings. Even in that case the distinction is very frequently not observed, to the extent that modern dictionaries record them as being used as synonyms.

If you wanted to use those two words in the senses you describe you would need to explain that usage before doing so. Otherwise the reader/listener would assume they were synonyms.

Something disorganized either had its organization removed or lacks organization; something unorganized never was organized or lacks organization.

First, a clue to some difference between the two comes through in each word's etymology. From the Oxford English Dictionary, disorganized has an etymology that suggests it can have a more active sense of something ordered being disorganized:

Unorganized: un- prefix1 + organized adj. Compare disorganized adj.

Disorganized: disorganize v. + -ed suffix1.

Disorganize is a verb that means to disrupt the order of something (Merriam-Webster). Consequently, as an adjective that was formed from the verb, disorganized may suggest that something formerly with order has been thrown into disorder. The Oxford English Dictionary for disorganized includes verbs suggesting some kind of loss:

Deprived or destitute of organization; having lost, or being without, organic connection or systematic arrangement; thrown into confusion, disordered.

However, note that disorganized need not be something made disordered. The unbolded terms destitute of organization, being without organic connection, and disordered suggest that something could lack organization from the start. In Merriam Webster's example sentence "The meeting was very disorganized," nothing suggests whether the meeting was always disorganized or whether it became disorganized. Contexts allow for either case.

Meanwhile, unorganized doesn't come from a verb and serves as a general description of a state. The verb unorganize (sic) does not exist in the dictionaries I consulted and it is relatively uncommon as a search result. Something unorganized lacks organization (Merriam-Webster).

So the two terms are somewhat differentiated, but that differentiation is subtle. My desk may be either disorganized or unorganized, but it might be odd to describe a routing army as unorganized unless they were unorganized from the start. Disorganized would describe that the army had been put into disarray.