Mode #1 is Average Voltage, and like most mods running these chips, it runs "hot" in Variable Voltage. Some vapers interpret this as "hitting harder", but that is simply down to the mod using Average Voltage in Mode #1, which doesn't really reflect the actual voltage that hit your coil.
Mode #2 is RMS Voltage. This mode uses the RMS (Root Mean Square) algorithm to determine output voltage under load, and is much more accurate than the Average Voltage method. RMS voltage readings are lower than average voltage readings, and this is likely why when you switch from Mode #1 to Mode #2, the vape seems weaker.
Mode #2 (RMS) is much more accurate, and in Variable Wattage mode, it delivers a more consistent vape, regardless of atomizer resistance ... 4.6 Watts into a 3.0Ω coil is only actually delivering about 3.7V; to get the equivalent vape of 4.6V into the same atomizer, you'd need to bump the Vamo up to about 7 Watts.