What is the basic difference between Radar Screen, CRT and Oscilloscope displays? What is the basic difference between Radar Screen, PC CRT Monitor, and, Oscilloscope displays?

All of them use CRT. So, what is the difference?
At many places in CG hardwares and algorithms you have the choice between vector description and raster description. Oscilloscops, radar, lasers shows, plotting tables, laser cuts directly follow lines and curves; these are the vectorials devices. LCD, inkjet and laser printers, stereolithographic 3D printing, follow pixels and voxels; these are the raster devices. The CRT, but also some laser shows, use the oscilloscope technology to implement raster: the "curve" is a repeated Z narrowly sweeping the screen line after line, with intensity modulation making the "pixels". Radars are indeed between this and pure vectors since rotation angle is swept. Details about various forms of radar display and oscilloscope is available on the wikipedia page.

( About representations, the vector/raster dichotomy corresponds to inkscape/illustrator vs gimp/photoshop, 3D meshes vs 3D voxels, list of lobes vs angular or SH decomposition, Lagrangian animation vs Eulerian animation, etc. )