In many places, snack items are available as desserts but not the other way around.
For instance, at SSR the desserts included carrot cake, chocolate cake, some pies, etc. THese were not available as snacks. Snack items included brownies, cookies, cinnamon rolls, etc. You could choose one of these as a dessert if desired. All of these can be boxed "to go."
Some places will stamp your receipt and allow you to come back after you eat to get an ice cream dessert (so that it doesn't melt while you eat.) WHen you get the ice cream, they tear the receipt to indicate that it is used. There is some sort of time limit as to how long you can wait to come back--but we were able to come back 2 hours later! CM said "same meal."
As above, snack items are labelled as such. Some beverages may also be available as the beverage with a CS or a snack. A yogurt parfait was available as a snack, not as a dessert. Ditto for small salads and fruit.