Cloud hosting offers you high availability solution, while shared hosting does not offer that.
Cloud hosting requires a robust infrastructure compared to Shared hosting.
I'll simply explain it with a example:
Shared hosting is like a post paid plan of Telephone where you have to pay a fix sum of money with the barriers of resources just like data, calls and SMS but when you get a
Cloud hosting with same plan but here you'll not have the barriers you can use more data than allotted. So technically you'll have to pay for extra usage in cloud hosting which makes it more expansive than share hosting.
The cloud hosting is a dedicated hosting service that allows you to manage and maintain your website with in a server that is only dedicated to you. But in a shared hosting the user has to share the server resources with other users.
Shared hosting companies have already invested in bulk infrastructure and at the level these companies operate, they have huge negotiation potential to lower price for bandwidth as well as disk space.To remain viable and compete in cut throat competetion they keep their prices low.The only drawback is that you get an about average performance from these shared hosting environment,still it is more than enough that you require for most of the websites. Cloud hosting is totally a different ballgame.They are the latest buzz and certainly they are not targeting the low end customers.Cloud hosting is more suitable where you need to use the high end spec,servers for shorter span, or where there is a continuous requirement for extra resources from time to time.Cloud hosting is very much flexible in terms of quality of resources as well as control of resources. For high end web applications or for corporate softwares cloud is the right game, for websites shared hosting or a good VPS is all you need for best pricing.
Well traditional shared hosting are setup on single physical machine and are been shared by multiple users is quite similar to a personal computer with multiple users whereas cloud hosting is refer to a computer network with a account been access at multiple systems. Well shared hosting is not recommended neither best option to start your business but unfortunately professional run after just because to cut the cost. Well there are some well known providers like: DigitalOcean, Linode, Vultr, AWS, Google Cloud Platform and few managed Siteground, Cloudways and A2Hosting. Cheers