Each mode is set up with a frequency spectrum (MultiIQ) that favors certain types of conductors and has software algorithms and user settings that enhance the resulting signal you hear assuming certain environmental conditions. The MultiIQ frequency spectrum is comprised of a combination of all 5 frequencies but the processing for each mode "favors" or weighted towards either the high or low frequency signals, even though it "listens" to all the frequencies. It works out like so (forget about what minlab called the modes because I think that just confuses things).
Park 1 is weighted towards the lower frequencies in the spectrum and therefore favors high conductors like pure copper, silver, and clad coins which tend to be detected better/deeper at low frequencies like 5 and 10 khz. Regardless, all five frequencies are still used so you are also still going to hit on mid conductors like nickels, brass, aluminum and even gold. This is probably the best "all around" mode to use and to learn the machine with. Probably best for coin shooting in parks and athletic fields.
Park 2 is weighted towards the higher frequencies and will hit harder on the mid-conductors (nickels, gold) and small targets (earrings, pendants) than Park 1 but will still hit on the high conductors too, perhaps not to the same depth as Park 1, though. Good mode if you want to zero in on jewelry, especially gold jewelry. But will hit small silver and copper jewelry and also coins as well. Some like to use this mode for relic hunting, too.
Field 1 is similar to Park 1 in that it is biased towards high conductors, but is a two tone mode. Have not used this mode at all.
Field 2 is similar to Park 2 in that it is biased towards mid-conductors. It has slight differences in ferrous/non-ferrous tone break and recovery speed vs. Park 2. This mode is my favorite relic hunting mode and the mode I have found the most old silver with (because that silver was in the same fields as the relics I was hunting).
Beach 1 is biased to high conductors and is for dry and wet sand salt beaches. Great mode for beach hunting. Don't be fooled by the fact that it biased to high conductors, it will find gold, too.
Beach 2 is able to deal with the ground phase effects of changing salinity better than Beach 1 and is suited for salt surf and underwater detecting. Same targets as Beach 1 but under water.
The Gold modes are very different than the other modes in that they use VCO audio which varies pitch and volume based on proximity to the target (similar to pinpoint mode). Gold 1 is suited to milder ground and Gold 2 is suited to more mineralized ground. The both are optimized for gold so, again, even though they are multi-frequency, they favor the high frequencies (mid-conductors).
Each of the modes are very different in how they sound and behave. Therefore, I would stick with a single mode to learn the machine before mode hopping. Because the machine uses multifrequencies, it is unlikely that you will actually be missing out much despite the fact that the mode may "favor" certain types of conductors. It still sees practically everything.
Don't mess with the single frequencies. They are purely there for backup purposes or to help with interrogating certain targets. I have never used the single frequencies. Examples, sometimes strong EMI situations will interfere with the MultIQ so you may find that going to a specific single frequency knocks down the EMI. In that case you can still detect, but you are limited by the single frequency you have chosen and some MultiIQ features will not be available like Iron Bias which can help reducing falsing by small iron (bent nails, round iron). Therefore, I would never use single frequency extensively unless I was forced into that situation since you lose the true benefit of the Equinox, Multi IQ and what that brings to the table. Some folks also use the single frequencies to to interrogate targets. By seeing how the VDI changes when you switch from MultiIQ to single frequency, you can ferret out junk targets like bottlecaps. I don't bother with this cumbersome method, but use the ALL METAL pushbutton instead to see if I can hear an iron grunt along with the bottlecap high tone, that is a giveaway that it is not a coin, as coin audio is pure.
HTH.
