I've read some Ladino and the only immediately apparent difference is the spelling and a few foreign words that have entered the language. They don't speak in formal polite form (as opposed to Latin American speakers of Spanish), so in that regard, it's closer to Castilian Spanish.
For example, what happens to orthographic G before I or E? I think Ladino has [ʒ] there.
Does the orthographic X become [x] or is it [ʃ]? eg. How would they say Quixote, with a "sh" sound?
Many years ago I found some recordings on the internet and I think it had both of these "old" features. And maybe some new ones, there was something funky going on with nasal consonants, eg. "muestro" for "nuestro".
Interesting, I once came across the original spelling of Mexico: Mejico. In Brazil today they call it "Meshy-ko."
Similarly in English, many of features that the British like to look down their noses as "Americanisms" were invented in Britain.
Another similar story I heard about English is non-rhotacism in the northeastern US. The British took north america pronouncing all the Rs. Then they dropped some. Then some northeastern cities did too. At least, this was the simplistic version I heard.
(Another favorite part of the OP works is the discovery of "lost" puns and dirty jokes due to pronunciation shifts.)
Similarly related, there's the interesting belief/possibility that a time travelling Elizabethan-era speaker of English would feel more kinship to the sometimes maligned contemporary US Southern accent than most other contemporary English accents.
Guessing it was one of constant contact, the Spanish were active sailing back and forth busy looting the Americas, while the Bosnians had lost contact. In the old days, sailing was probably much more efficient than horseback across a mountainous continent. Why didn't they sail over to Croatia? Not sure, perhaps Ladinos weren't active at the coast? Also, religion probably divided them from most Spanish.
yeísmo is also present, which is at present just about absent in Spain, except perhaps from the older speakers in the south.