AWS have at least 32 DCs - all regions have a minimum of two data centres for proper ha. There are four more scheduled to come online this year, India and UK.
If you think ovh and aws are comparable in anything but the very broadest terms you've not understood what AWS are offering.
OVH currently has 15 DC, of those additional 12, most of them are in new region, Australia, Singapore, Germany, US, and I think Japan. That will make 27 DC.
This isn't say they are comparable by size. Not at all. But you make it sounds like OVH is a small player. Linode, Digital Ocean are medium size. According to Netcraft AWS being first, DO recently became second, and OVH being third. But with the lots of $5 - $20VM DO host, those are VM numbers, compared to the Server Size OVH host.
I would also add that since OVH own and operate a large physical network[0], they can't really be compared to a hosting-only provider like DigitalOcean. This isn't 'like for like', and is only marginally useful for ranking either company.
Also, for those of us looking for server space to serve a primarily Western market, OVH and AWS are most definitely comparable. AWS have a huge and impressive range of features, most of which I simply do not need (though I'm a happy OVH, AWS, and DO customer because I'm not one to put all my eggs in one basket).
Not sure if everyone realizes this, but often (outside the US at least) neither company build or owns data centers. For example, Amazon Sydney is in Equinix SY3[1].
I'm guessing Equinix aren't allowed to say AWS is in their DC.
But their equipment is in there, 100% guaranteed (or at least was in 2012).
Edit: Here's a better reference:
Equinix yesterday launched phase two of its Sydney 3 International Business Exchange datacentre facility (SY3-II) in Alexandria, with Amazon Web Services (AWS) onboard as one of its first customers.... It was only confirmed yesterday — despite it being the worst-kept secret in the industry - that it is using Equinix's SY3-II datacentre.
AWS have two dedicated DCs ('AZs') in Sydney. For services that require quorum (Dynamo, SQS, S3 and others) they also have a private third 'AZ' in SY3-II. When you get an EC2 instance it is always in a dedicated DC, not Equinix.
I don't know about OVH. I know OVH built their Quebec DC, but I'd be surprised if their expansion plans don't include leasing space (if they don't already do it).
If you count edge locations (where stuff like anycasted nameservers, cloudfront and network PoPs are hosted) as well then the DC count is significantly higher than that
Don't forget the availability zones! Each region has 2-4 availability zones, and each of these has 1-6 datacenters. The scale of AWS is at least an order of magnitude more important than OVH's.
It's not uncommon to use multiple providers, that way you don't need to rely on a single provider having multiple DC's in every location you want a presence.
