On Premises(data center)

1. Servers are computers with high-end configuration(CPU, memory, and storage) which run non-stop and still work efficiently.
2. Data center is a place where we have multiple server room to store servers.

Maintenance

Capital expenses

Cost of products and services needed to keep the servers running uninterupted:-

1. Power
2. Temperature
3. Security
4. Networking

Operational expenses

Cost to maintaining those servers also which are currently not in use. In data center some servers are in use and some are not in use currently but they need to maintain all the servers so the expenditure of maintaining inactive servers also is operational expenses.

Cloud

1. Cloud is renting of servers
2. No maintenance expenditure only the rent for the servers
3. Easily increase or decrease number of servers as per requirement

Conclusion

1. on-prem is expensive while cloud is cheap
2. on-prem needs maintainance while in cloud, provider takes care of it
3. on-prem needs physical space while cloud don't
4. on-prem setup requires time while cloud is just like plug and play

Real life example

You rent a fully furnished flat where you get a bed, AC, wardrobe, lights, fan, kitchen setup, and other amenities. You can shift in today, pay the rent, and start your work without worrying about the facilities or maintenance. In contrast, if you buy land, build a house, purchase furniture, electronics, kitchen utensils, and so on, it requires a longer time, greater investment, and ongoing maintenance.