It is easiest when trying to count. Although 3/4 and 6/8 look superficially similar how they are counted differs much.
Think of 3/4 as a waltz rhythm. How do you dance the waltz, it is 1,2 1,2 1,2? Think about how the dancers move when they dance the waltz.
A compound Time Signature now has pulses with dots next to them but the underlying number of pulses remains the same.
So remember 6/8 time is Compound Duple Time it is, in fact, more similar to 2/4 time than 3/4. The only difference between 6/8 and 2/4 is that instead of crotchet beats you now have dotted crotchet beats.
So 6/8 time you will count 1,2,3 1,2,3 with the emphasis usually on the first beat.
Now about triplets. Triplet does not change the beats, you still have exactly the same amount of beats you just play a certain amount of notes instead of the regular.
So in 2/4 with triplets, you would still have your two main crotchet beats you will only really play three notes in the time of one beat. (For quaver triplets at least.)
In 2/4 time with triplets, you would count 1,2 and just play the three notes in a beat but with 6/8 time it is just 1,2,3 1,2,3. So there are differences in the way you would approach playing those rhythms.