An interesting point came up yesterday while I was having a lesson Peter Kent over in Montpelier, VT, and that has to do with one's piping style. Beginning pipers usually have just one instructor during the formative years, and so will adopt the instructor's style whether they realize it or not. It's easy for those who don't listen to a lot of piping to not identify different styles and classify anything different from how they were taught as "wrong."
Stylistic differences aside, there are things that everyone agrees are "correct" about piping: note fingerings for example, which gracenotes make up each embellishment, tuning, that kind of thing. Every decent piper will play notes with the correct fingering, pipes tuned, and technically correct embellishments. Not all pipers do this, but I'm not talking about them here.
Beyond that, however, there is some wiggle room. If we just look at light music, here's a few points for argument: light or heavy D throws; strathspey pulsing of strong-weak-medium-weak, or a different approach like strong-medium-medium-strong; really tight doublings with the gracenotes immediately following each other, or with more spacing so there's an actual note between them; emphasis in reel playing on the beat or the offbeat; round, pointed, or pulsed jig playing. These are different from piper to piper, and even from tune to tune played by the same piper; there are a variety of answers for each of these point, and many others too.
The real answer, though, is that nothing is wrong as long as it is a) consistent and b) musical. I personally prefer to play heavy D throws in light music; I just don't like the sound of the light D throws. Willie McCallum, on the other hand, always plays light, and
obviously it works for him. As long as you play the same kind of D throw throughout a tune, it's not wrong. Extended to doubling, it's common to play more open doublings toward the end of each part of a march than at the beginning, for example, but you had better play them the same way on the repeat.
The point of all this is that there are different styles of piping, and anyone who tells you that all pipers try to play things exactly the same hasn't heard enough piping to see the different styles. No style is correct or incorrect, but we have our preferences. Ideally, through a piping career a piper will have several instructors from different backgrounds, and listen to recordings of many pipers, and will combine bits and pieces of each to slowly form his or her own style. Developing one's own style is a slow and usually subconscious process, but by hearing others play we get a sense of what we like.
It's tempting to say I want to play a 2/4 march like
Angus MacColl, or strathspeys and reels like
Alasdair Gillies, or piobaireachd like
Roddy MacLeod. It's not really wrong to say that, since those guys are really, really good at what they do, but it's like being in a tribute band and playing someone else's music instead of writing your own. Copying another players style isn't unethical, just unoriginal. It denies the essence of music. Everyone plays the same notes, but each musician adds his or her own stylistic interpretation, a personal touch, and transforms the notes into music.