There are a few types of moss. Some grows only on land, another grows only in water. Some species of moss are found in both and can adapt to as long as the environment is humid. If you wish to collect moss from the wild, the best aquatic moss are those found immersed in clear running waters and streams. 2nd best is the moss that grows on rocks just on the water level. Do not collect those that are found on the sides of drains because they contain a high level of pathogens, bacteria, mold spores, yeast, protozoa, fungi and algae.
Moss grows beautifully especially in cool temperates between 20 to 28 degrees celcius although it can tolerate up to 30 degrees celcius.
Water parameters like pH and hardness are not important since moss is a hardy plant. The only problem you might have is it may grow out of control without regular trimming!
Moss is not only beautiful when attached to driftwood, rocks or wire mess, they also provide hiding places for fish and shrimp fry. Being fast growers, they are also useful in soaking up some of the excess nitrates formed from the nitrogen cycle.
Generally, moss is regarded as low requirements plants that grow easily.
Proper identification of moss is made by using a microscope at the cellular level. However, obviously you don't carry a microscope with you all the time so the following helps with the moss identification:
Java moss is the hardiest of the common aquarium mosses. Their characteristics is they grow in long 'strings'. They can get untidy if neglected because they graw in all directions. However, java moss is beautiful if regularly trimmed. Since they are hardiest, they are likely to be healthy and green. Other supossedly more beautiful species of moss are less hardy and if your tank conditions are not suitable, they will be unhealthy and not be as beautiful as healthy java moss.
Christmas moss has shorter 'strings' and denser branches that makes up the triangles. They are still quite long though. When left untrimmed, they grow upwards towards the light. In this upwards presentation, christmas moss is sometimes sold as 'erect moss'.
Taiwan moss has even shorter 'strings' than Christmas moss so the fronds are like triangles and not stringy anymore.
Minimoss has such short fronds and dense branching that they don't have triangles but grows in a dense mass.