The other measure sounds more like a 3+3+2 additive measure than a division of 4 or 8 beats into 2 or 4 (or 3 in the question). (As mentioned in other answers) the triplet sounds like a smooth 3-beat bar because it's written as a triplet (rather than as a 3/4 measure with a slightly slower tempo), this structure is useful as a contrast to a piece written in 4/4 with a 4-beat bar (or 2-2 with a 2-beat bar.) I, personally, love this "slowing down" effect and use quite often. It's quite common to have a part of the piece that has triplets all the time, so the composer would add the dotted eighth to create a small difference in this specific passage, or vice versa, when a piece has a lot of sixteenth notes, adding quarter triplets might feel like the piece is "slowing down". It would also depend on how the rest of the piece (or part of the piece) goes. For me, the triplets have a more laid back feeling and the dotted eighth has a more sharp feeling. If played correctly, they have a different feeling and the choice depends on what the composer wants to do. Now as far as which one to choose, it would be totally up to the composer.
![dotted quaver dotted quaver](https://www.schoolofcomposition.com/wp-content/uploads/2017/08/6-dotted-eight.png)
The difference isn't that big, and an amateur player might not be able to hear/play it, but it is there and it is important. This is because in the case of the triplets, you divide the beat by 3 (and play the first and third note), whereas in the case of the dotted eighth, you divide the beat by 4 (and play the first and fourth note).
![dotted quaver dotted quaver](http://www.clipartbest.com/cliparts/di7/eA8/di7eA8x7T.jpeg)
The following are the exact same rhythms you posted, but each one is divided into smaller values and they are placed on top of each other to make the comparison easier.Īs you can easily see, the two notes you said don't fall at the same beat.