Gujarati vs Hindi: what actually changes
Knowing Hindi gets you maybe halfway into Gujarati, which is the problem. The overlap makes you confident, and the differences sit exactly where meaning lives: who did what, to whom, and whether the thing is masculine, feminine or neither.
The four that matter most
Three genders, not two. Gujarati adds neuter, ending in -ũ. ઘર ghar, નામ naam, પાણી paanee and પુસ્તક pustak are all neuter here. Importing the Hindi gender is the single most common error.
The swap. ને ne is the dative and object marker, the job Hindi gives को ko. The ergative, Hindi's ने ne, is એ e in Gujarati. Same shape, opposite job.
The copula. છે chhe replaces है. The negative is one fused word, નથી nathee, not two.
Two words for we. આપણે aapane includes the person you are talking to, અમે ame excludes them. Hindi's हम does not make you choose. Gujarati does, and choosing wrong is socially audible.
Straight conversions
Same job, different word. Learn these and a lot of Hindi sentences convert cleanly.
Everyday words that are simply different
These are frequent enough that missing them is why spoken Gujarati sounds unfollowable even when your Hindi is decent.
One sound to keep
Gujarati has ળ, a retroflex l that Hindi does not use. It shows up in ordinary words like કાળું kaaLu~, black. Flattening it to a plain l is the accent giveaway.
So which should you learn?
If the family speaks Gujarati at home, learn Gujarati for the house and Hindi for everything outside it. Hindi gives you films, travel and most of the internet. Gujarati gives you the kitchen, which is where the conversations you actually want are happening.