When a rangefinder reads the first object in its line of view and ignores further objects, the rangefinder is said to be in a first priority mode. If it ignores the first object and sees past it to a more distant object the unit is said to be in a second priority mode.
Priority Differences
The First Priority Rangefinder is extremely useful on the course. If the flag isn't hidden, there is usually nothing between you and it. All rangefinders have the first priority mode. If you want to range at a flag located about 100 yards away, the flag will display 100 and not 130 which could be due to the trees behind the flag.
Second priority rangefinders are more useful for hunting. The second priority rangefinder, as described in the previous paragraph, would read the trees at 130 meters and ignore the flag 30 miles closer. Hunting situations often require you to be in a blind, or partially covered by leaves or limbs. The hunting rangefinder or second priority rangefinder would ignore any object within its line of sight, such as branches, and instead read the closest object, which could be a deer.
Can you use a golf rangefinder (first priority) for hunting? Absolutely. Can you use a hunting rangefinder (second priority) for golf? Certainly. But the product most closely designed for your intended purpose would be more user-friendly and not require multiple readings or switching modes to ensure the correct distance. Some laser rangefinders allow you to switch between second priority modes temporarily using a "bullseye", "pinpoint" button, or semi-permanently by switching priorities semi-permanently.
Distance
Rangefinders are sold and marketed under names that imply the maximum readable distance capable with that unit. This is the biggest misconception consumers have about these units. A unit may be labeled as a 1500 yard rangefinder, and it may be, but only under ideal atmospheric conditions on highly reflective large surfaces!
For instance, without a lot of glare and air pollution and heat waves on a cool day under a cloudy sky, you may be able to range a smooth white metal pole barn at 1500 yards. If you add sun, rain, snow, heat mirage, or reduce the target's size, or darken or increase the color or texture, then NO! You may see hundreds of yards less. In perfect conditions you may see your Click Here pole barn at 1500 yards, a dark rocky hill at an oblique angle at 1100 yards, a huge truck at 900 yards, a tree at 700 yards, and a deer at 450 and a flag on the green at even less. Most times a deer may be read at around one third of the maximum stated range, and almost always well under half the distance. Check the manufacturer's specifications.
Reticles and Aiming points
A Reticule is the crosshair or aiming point/circle that you see in your rangefinder. Some reticles have black lines you can superimpose on the object you wish to range. These reticles are often impossible to distinguish against a dark background, or in low light conditions such as shadows. Some reticles (or aiming points or circles) appear illuminated because they are actually LED lights. These LEDs can be adjusted in brightness. The issues with LED reticles is that in bright conditions they may be drowned out by the ambient light so they cannot be seen, even at the highest settings, and in the evening, when your eyes are accustomed to the night, the reticles or circles are so bright that they destroy your night vision even at the lowest settings. The bright reticle is what blocks your vision. The aforementioned issues with reticles also pertain to other information within your viewing screen such as yardage numbers and modes.
The best of both worlds, in my opinion, is a black reticle and information with a button for backlighting. Backlighting is less intense than an LED and allows you to see your information in any light condition.