I'm sorry for resurrecting an old thread, but I was born here a couple of months ago. After spending some days reading this thread, finally I will post my thoughts.
Actually, I've been all my amateur magic life involved in this concept: the contrast between the professional and the amateur.
In the book I wrote (link below) about card magic, I talk about this concept all through the book. So, I could copy and paste tons of those staff here in this post! But I prefer not to be so lazy and write an overview of those thoughts of mine about it:
An amateur can be as good as a professional, and a professional can be as good as an amateur
So, regarding quality it doesn't have to be any special diference. Nevertheless, there are important diferences anyway, and I thought about three principal or important diferences between both sides:
1° Professinals are more than motivated. Magic is their life. They devote their life to the improvement or the effects and care about the spectator reaction to the utmost. Whereas, we amateurs are not so motivated, so we can felt into the laziness. Professionals only get along with the perfection, whilst we can be content with the "more or less good." And it can drive us to be a seedy magician.
Professionals not only do good magic because they love magic, but also because it's their job. Their life. Amateurs can love magic to the point to do a really good magic, but always will be lack of the same intensity of motivation of professionals, and we should strieve to not let it affect us too much for the sake of our performances if we want to seem a "real" magician.
2° Professionals can devote 24 hours per day to magic.
3° The most important of the three concepts is the point of view of the spectators.
Spectators of professionals (SP) are quite diferent to the spectator of amateurs (SA).
In my book there is an entire chapter devoted to this concept. I could write pages and pages talking to this concept, but I will do an overview.
SP consider tha the magician is a "true" magician. What is to say, they are just magicians and nothing less, whereas SA consider that the magician is a kind of impersonator magician; someone that only try to imitate a magician. This point of view brings a lot of special consecuences very negative for the amateurs. I analysed them carefully in the book.
I can not say I'm a specialist in this field, but I can say that I have devoted or focused my card magic life to analyse those both point of view, for the sake of the world of the family or plain card magician.