Green lasers, although more expensive, are EXTREMELY bright when compared to red lasers. It is easier to see green lasers in daylight, but you are still going to need a laser-reflective background to be able to see any laser.
I have a green laser on an urban carbine, and from experience have found that railroad ties, some fleece fabrics, some stonewashed black denim, among other items, are poor reflectors. On the other hand, 5.11 in black lights up to the point of being blinding. (It could be additives in laundry products, but I'm not intetested in doing the research to find out.)
If you get a green laser & want to play with it, DO NOT point it up in the air or at municiplal structures like water tanks. FAA, FBI, and lots of other initials are out there watching & have arrested folks for "targeting" those sorts of things. From what I hear, it is not funny to be lit up by a searchlight or have a dynamic entry in the early morning hours. Also, the alibi of "it was my daughter playing with it" did not fly for one guy in NJ who was indicted for lighting up planes flying overhead with a "small" pencil-type green laser pointer.
stay safe.
skidmark