The term carry-on refers to a bag that is designed to be carried on board an aircraft, typically with a maximum size limit. On the other hand, a suitcase is often larger and more robust, designed for checked luggage. But, if your carry-on is large enough to hold all your clothes and toiletries for a week-long trip, can't it be considered a suitcase?
Let's consider an example: imagine you're going on a weekend getaway and you pack a small bag with just the essentials - a change of clothes, your phone charger, and a toiletry bag. In this case, your carry-on is probably not a suitcase. But, if you're going on a longer trip and you pack a larger bag with more clothes, shoes, and accessories, it's likely that your carry-on can be considered a suitcase.