The biggest difference is that road pedals generally have a securely locked front engagement with the latching in the back. As such they are very resistant to vertical pull out, but entry is a bit different, in that you have to slide the toe froward to latch the front before stepping down.
Mtn clipless is more of a vertical press down to latch, and slightly easier to release. But keep in mind that all pedals have adjustable release force.
Then there are pedals with unique designs like Speedplay, which can be pricey but have very easy engagement.
One other consideration, depending on how, why and where you ride. Mtn clip style shoes usually have the cleat recessed in a shoe that's pretty OK to walk in. So these are better suited to commuter and utility rider than typical road shoes which are highly unsuited to walking.
As to brands, make your own choice based on your budget, but put heavy emphasis of the reputation for quality and reliable release force adjustment. Weight is less of a concern.
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