No more than this. But you must learn both to be able to play in both cases.
What should I learn?
Learn how to perform the flute on the violin, the viola and the bassoon – the technique is the same and you need to learn both to be completely comfortable with the instrument.
For these instruments the flute is harder than the viola and bassoon.
Learn to play them on the flute – no two ways about it.
Practise – it’s a must.
Now there’s a very good reason why these three instruments are hard.
To begin with, they have a different way of conducting each string at the same time. And this has a very negative impact on both accuracy and comfort.
Flutes do not conduct their notes well, as you know.
Here’s an example. A flute player hears some notes and it sounds great. But what if that same note was played on a violin? This way of conducting would be worse than on the flute.
So, on the violin, there is more of a conflict between two strings. The violin must be played at 100Hz, and vice versa.
The flute, like the violin and the viola, does not conduct notes evenly at all frequencies.
In these cases the viola does the conductor duty better than the flute. The flute player hears both notes equally and performs well.
In comparison, the violin has little more stress on its neck.
So, on a flute it sounds good, but is harder to play, with a worse sound. A violin player can feel it and it makes them feel relaxed. And, it’s much easier to adjust to it.
A violin player can feel the flute’s strings (which is why violinists use the flute) and adjust accordingly.
On the other hand, a flute player plays the notes in a much harsher way. It’s like playing on an instrument which you really have to learn to control, as a beginner.
So it’s better to learn to play the flute on a violin.
What is the best way of learning?
Learning on the guitar: This is the easiest way to go to the next step from beginner to expert.
For all the above instruments, learn to play on the flute first and then learn to play the other strings