Are radar resolution and detection capabilities not very tightly related?
Resolution is (usually) referred to as the ability to distinguish two closely separated returns, not targets. 

The distinction is how far along the processing chain of the radar you are, resolution, given by the inverse of the bandwidth is often limited by the hardware (waveform generation, filters, amplifiers, sampling..) and the environment. While Radar detection is done as a further processing to distinguish between what you want to see (targets) and clutter (birds, ground, sea, trees, ..) edit: and is usually limited by the signal to noise/clutter ratio. The detection step will usually contain multiple looks.

You can therefore have say a really good resolution, but since all you see is "noise/clutter", you can't really detect the target you are looking for. Edit: Conversely you may have a really good detection algorithm that uses say excessive averaging and multiple 'looks', but if your resolution is poor, two closely spaced targets may appear as a single target.

Edit: Note that I use noise and clutter interchangeably, as it simply refers to what you don't want to see.

Edit: To simplify things: resolution will depend on the bandwidth, while detection will depend on noise level and processing.

I have attempted to sketch a generic radar system below, the resolution is given by the receiver output, while the detection algorithm will typically use multiple looks (for averaging and doppler discrimination) and use a threshold to alert the user of one or more target.