To continue the last part, following we tell you more common about laser

Green laser are usually fixed focus, beside blue laser sometime do focusable, and some not. But nowadays this is the problem of cost but not of lacking of technology.

Focusable laser is much better at burning stuff because of their extremely high power density. That remind us that the laser device must have well-trained people of operation.

Blue laser have horrible beam specs and a divergent, rectangular beam, which is usually appearing on entry laser system used for daily entertainment.

Green laser has varying beam specs, where high quality laser has a near circular beam. That may give you smooth and fine laser beam in the air, some high class sky laser projector can even have bright visibility 5~7KM of distance.

Green laser can be unstable while blue laser is very stable, that is another reason of why blue has how nice cost performance ratio.

Blue laser is often in the class 4 range and is nearly too dangerous to have fun with. Eh, if you want to act a Jedi perhaps it is a nice choice, only if you can brandish it for it can be 20KG of weight.