There's benefits to both.
- Zomato has richer food imagery that is meant to portray how mouth-watering the food is and tempt the user into taking action. Remember that Zomato started as a restaurant reviews company, so that line of thinking reflects into the app.
- Users do like more options to choose from. Plus, more results within a viewport improves navigation and scrollability. But someone else pointed out that more options lead to higher cognitive load. That's definitely true but I think it may not have reached that point where it would make a difference. Plus, Swiggy started as a convenience app and it is known in the industry for its logistics. So again, the convenience of exploring more options reflects in their design and layout.
The success of each layout would depend on the mindset by which the user enters the app. Is he in the mood of indulgence, or is he in the mood of exploring the best, fastest, cheapest etc.