The first one is the New Zealand Strike Indicator. This indicator is wool, it floats high and is very sensitive. I have been using this indicator during low water, calm water, and while using small/smaller flies to wary fish. The indicator lands softly on the water, will detect subtle takes and can be moved up and down the leader with ease.
The other one is the Airlock Strike Indicator. This indicator is similar to the thingamabobber, but doesn't kink your leader as it uses a nut to hold onto the leader. This indicator is best for more turbulent water and heavy nymph rigs. It lands on the water with a plop, isn't as easy to cast, but is my go to indict or for big water deep nymph rigs.
I'm a minimalist by nature, but by having these 2 indicators in your vest you will be covered for any situation you may find while on the water.