Advantages of single VPS -
VPS is your own server with root access. You can host anything on it as it's your server. You can have any applications, software. You will have the bandwidth, resources, inode only for your service, it won't get shared with any other server. You will get dedicated resources for your service on VPS. You can manage the server in your way.
Server will have good up-time and security measures if you will manage it from your end as there won't be interfere of other service. You will have root SSH access too.
Advantages of cloud VPS -
1. Accessibility - Main advantage of cloud hosting is that the files are accessible anywhere and anytime. You can access the files when you would like to access without matter of place.
2. Backup facility - Cloud hosting service always have the copy of your data on the the server. So in the case of disaster, you will have the copy of data even if the data on the main server get deleted or lost.
3. Low cost solution - You will need to pay just the amount for the storage which you are actually using.
4. Secure service - You don't have to worry about the security. Cloud hosting provider will have the best infrastructure on which you don't need to worry about the security , they have their setup for security.
5. High degree of uptime
Disadvantages -
Main disadvantage of single VPS is that when you would like extra resource or extra space that time you will need to contact your hosting provider for it. On Cloud hosting service, you will be charged for the storage space or resources which you are using so you don't have to worry about the extra bandwidth or resource.