Yes and no to both;
1. Is Cloud Hosting safer than Traditional Hosting?
A. No. Both are connected to the Internet. True cloud hosting is a Virtualized container platform; it is only secure as you yourself make it. Traditional Web Hosts (Shared) may be a safer alternative as they spend a great deal of time making sure that the systems are secure and optimized for best performance (depending on the host). So it's a pretty vast question you asked there. It can either be safer (i) if you are better at securing the platform than the next person; or (ii) it can be the most insecure, bug-filled not-working crap that you've ever used.... None of this is dependent on the host itself.
2. Is Cloud Hosting more reliable?
A. Yes and no. Who is it you are looking to get Cloud Hosting from? Is it one of those random hosts that *claim* they offer Cloud Hosting? How much are they offering it for? A couple providers I can vouch for that are truly utilizing Cloud Infrastructure are Rackspace, LiquidWeb & Amazon EC2 (neither of which are *cheap*, you're looking at a pretty penny). The above companies I have mentioned not only replicate data on-site, but also across numerous Data Centers protecting you that extra little bit... Traditional Web Hosts that offer "Cloud Hosting" use the term as a marketing ploy; a lot of them are offering simple Xen VDS or KVM VPS and store the user data on an external storage system, giving the appearance of Cloud Redundancy (some don't even do that, and just sell you a VPS/VDS as you would buy elsewhere. Finally, look at the answer of the other question you asked me. Once again, the host is only responsible for 40% of the service they offer you when it comes to Cloud/Dedicated/VPS unless you pay for a COMPLETELY MANAGED SOLUTION; this includes Hardware/Power/Cooling. You are responsible for the software. If you don't know what you are doing, no, Cloud Hosting is not more reliable.