John Carey at Fifty Foot Shadows, on Instagram and Flickr:
Instagram is built for casual, mass consumption and sharing mostly lifestyle photos. The reactions to these shots of day to day life and “look what I’m doing now” moments are decidedly more quick, friendly, ah ha! sorts of moments. Those using it to share more serious work simply have to come to terms that its a mixed bag of educated reactions within the service (same goes for using Tumblr as a means to share photographic work).
Flickr and other similar services, on the other hand, were built for and perused by a community of fellow photographers, both pro and amateur, and is not as much of a hangout for casual users. While there is still some of the same casual favoriting that happens on Instagram, you can expect your audience to be at least a bit more critical of what they are seeing simply because they are also photographers and in some subtle way, your competition.