1/What is different between the Planet Eclipse 170R and the HK Army 170R?
The HK Army 170R is the same marker as the standard Planet Eclipse 170R, it just has HK Army's limited edition milling and is available in a variety of different colors!
2/Is it worth it to buy a 170R instead of the CS2, aren't they basically the same marker?
Although yes, the 170R and the CS2 are very similar, they are still different. The 170R is a fantastic value, and features the same basic platform that the CS2 is built off of, however the CS2 will still be made to be the higher end version. It is no different than a standard vehicle, and one with all the upgraded options.
3/Does the 170R come with a soft tip bolt?
No, the Planet Eclipse 170R does not come stock with a soft tip bolt, however you can upgrade to the ST3 bolt, which is a drop in replacement soft tip bolt.