Here's an article to understand the impact of categories on different aggregators and the different constraints on each of them.

Swiggy:

• Swiggy has a simple and elegant UI and does not have many constraints for categories. It shows only the Main Category (Parent Category). 
• Sub Categories appear on clicking the parent category.
• Recommended: This category will only appear if you have configured the image and marked Is Recommended for an item. Sorting of items within this category cannot be controlled.

Zomato:

• Categories are listed on the left-hand side of the restaurant menu page.
• Bestsellers: This category is controlled by Zomato on the basis of the best selling items of the brand.
• Restaurant's Recommendation: This category contains a set of 10 items which are randomly selected and sorted from the entire list of items marked as recommended.

Category Timing

• If you have some categories which are only available only on certain days or certain at a certain time in a day, you can set the timing group for that category. You need to enable Support for Category Schedules by navigating to Configuration →Business → Swiggy/Zomato → Support for Category Schedules. (Article on How to configure Timing Groups?)
• Unlike Swiggy, Zomato does not have support for timing groups at a sub-category level.
• For Swiggy. the sub-categories will by default have the same timing as the parent category unless a specific timing is configured to it.