What you need to setup and maintain in different service delivery models:

                    On-Premises         IaaS            PaaS            SaaS

Software            Yes                 Yes             Yes             No
Runtime             Yes                 Yes             No              No
OS                  Yes                 Yes             No              No
Virtualization      Yes                 No              No              No
Server              Yes                 No              No              No
Storage             Yes                 No              No              No
Network             Yes                 No              No              No

IaaS product examples:

DigitalOcean
AWS EC2
Google Cloud VMs
Azure VMs

PaaS product examples:

Heroku
AWS Elastic Beanstalk
Google App Engine
Azure App Service

SaaS product examples:

Dropbox
Trello
Intercom
Slack

Sources

• SaaS vs PaaS vs IaaS: What’s The Difference and How To Choose