The very nature of mobile-sharing apps has changed the types of imagery that people upload. There is also an added on-the-move life-streaming nature to the whole thing. Photos found on the flowing Instagram news feed don't look like the ones you might come across on Flickr.

Instagram is a community conducive to likes and comments, whereas Flickr focuses more on displaying collections of photographs in photostreams, sets and galleries, organized by tags and maps. Yet interestingly, the most-used camera on Flickr is the iPhone4. What's fundamentally different about the two sites? The privacy settings.

"I've been using Flickr for six years now and have post almost 6,000 photos in that time and have almost 600,000 views," says Boston-based photographer Greg Peverill-Conti. "The main thing I use Flickr for is a project called 1000faces that's almost at 3,000 photos now. It's been great for storage, for having people find photographs and connecting with other photographers."

For Peverill-Conti, Flickr operates more as a storage space and ongoing project. He also shoots photos that he uploads to Flickr with a Canon T2i in RAW format, which in English is the highest resolution possible. He then uploads them with Flickr Uploadr or Lightroom. Instagram is more of an afterthought, for spur-of-the-moment stuff that he sees when he's out and about.

"Last night, for example, I was walking out of a movie theater and a guy was on a scissor truck changing the marquee," he says. "That I shot with my iPhone."

Photographer Chris Azar tells ReadWriteWeb that he sees Flickr as "a good space for my DSLR photos, and Instagram for grab shots and realtime stuff."

"I send Insta stuff to Flickr, too," he adds. "Instagram is almost exclusively mobile versus Flickr, which is exclusively desktop (& more studio work & creative commons)."

The two do not often share the same space. And why would they?

Public vs. Private Imagery: Instagram vs. Flickr

Instagram features the Andy Warhol-esque polaroids of our day. One perfect description of Instagram lives on Instagrammers.com's About page

"Instagram unearths your creative side and gets it flowing. It allows you to make artistic pictures even if you always thought you were the least creative person on earth, and last but not least, it makes you part of an international and multicultural community that is really into sharing."

And on Instagram, everything is public. Audiences appear and disappear almost as quickly as images on the stream.

That is not the case on Flickr, where users have granular settings for changing photos to public, visible to friends, visible to family or completely private. Communities are more deliberate. Following is not an option, but joining is.

Flickr provides a list of the most popular tags on the site. Not surprisingly, a few of the biggest categories include canon, instagramapp, iphoneography, nikon and wedding. The iPhone4 is the most popular camera of the Flickr community, just ahead of the Canon EOS 5D Mark II and the Canon EOS REBEL T2i.

The very fact that community members of Flickr have the option to upload from a point-and-shoot camera, however, changes the popular imagery that one is likely to see on Flickr.

The iPhone4 may be the most popular camera of Flickr users, but the four other cameras are not smartphones.

What Instagram lacks, Flickr fulfills: A possibility for adjusting privacy settings so that every photo uploaded doesn't appear out there, for the entire Web to see. On Flickr, there is no such thing as social media celebrity.

The public nature of Instagram makes the idea of celebrity not only normal, but encouraged.

Images via GregPC's Flickr, Chris Azar's Flickr, Followgram and Instagram.