I'll oversimplify, but it will give you a very basic starting point.
Both LR and Aperture are considered digital asset management programs that also have image manipulation capabilities similar to CaptureNX. They both allow you to store large numbers of photos and allow you to categorize and retrieve them them using ratings, colors, keywords, etc. Both also have significant tools to manipulate images. Similar to Capture NX. Neither really have any serious graphics capability at this time.
Adobe Photoshop CS6 and Photoshop Elements are more graphics oriented so you can draw on photos, create montages of photos, add different backgrounds, layer parts of one photo on another, etc.
I don't have any experience with PhotoNik and won't comment on that.
Hope that gives you some idea and again these descriptions are vastly oversimplified.
"Red is gray and yellow white, but we decide which is right ....and which is an illusion"