But what I don't get is this:
Why is there no detail in this pic, when it is 635x717 and 96.9kb and...
'Detail' is a relative term, and I think you are confusing it with sharpness versus blurriness. IMO your shot of the 2 dogs is out of focus OR if it was scanned, then it may not have been the best scan.
You must keep in mind that if the shot is out of focus or not perfectly sharp it will appear to have less detail.
The vast majority of digital cameras are point and shoot cameras and you cannot control the focus. The camera focuses for you and often does a good job...but not always. This type of focusing mechanism cannot compare with a traditional 35mm SLR or a higher end digital camera whose focus you can control.