Let's forget about the graphic and just go over what the diffrences between simple and compound time signatures which lies in how the grouping of each is done.
In simple time, you just have one grouping of notes per measuer like in 2/4 you have a group of 2 quater notes per measuer, 3/8 you have a group of 3 eighth notes per measuer, 2/2 you have a group of 2 half notes per measuer, ect.
In compound time, you have two levels of grouping. One level of grouping is to add another beat grouping, typically grouping in 3, to give the time signature more of a simple feel like the ones above and the other is grouping the remaining groups.
For example in 12/8, we group the 12 eigth notes into groups of 3 which we have 4 of total. We then look at the group of 3 eigth notes as a dotted quarter note and now we can break the measure up into a quadruple meter feel, but there is still the underlying groping of the eigth notes which is why we call them compound time signatures which is because we are using multiple groupings.
The diagram you came across is very confusing in nature because it approaches it from an odd angle at just looking at subdivisions in isolation which isn't the clearest way to demonstrate that. Try looking at Music thoery.net's lesson and see if that clears it up for you.