Last week we saw a digital SLR do battle with a high-end point-and-shoot—today the DSLR faces its hybrid challenger, the interchangeable-lens camera. The main difference between these two cameras is that the latter does not have a mirror to bounce the image to the viewfinder.
The major difference between these two cameras lends itself to the main advantage of a DSLR over an ILC. The viewfinder on a DSLR is superior and ensures there is no update lag. The mirror allows the photographer to see what is currently happening in the viewfinder, while an ILC can only show you what has already happened. The advantage to the EVF, however, is that it accurately displays exposure and white balance. Some optical viewfinders on DSLRs can do this, but it comes at a greater cost.
While there are certainly plenty of digital camera lenses to choose from for ILCs, the selection is still larger for digital SLRs. DSLRs also have the ability to use older film-camera lenses without an adapter. But with better technology and bulky lenses, DSLRs tend to be bigger and heavier than ILCs (though there are compact DSLRs, as well as large ILCs on the market).
The bottom line is that the ILC is a good stepping stone for consumers who want a step above their point-and-shoot but without the bulk and the high cost.