A dinner table discussion resulted from the quote “Give an amateur a digital camera and you have wiped out years of advantage of a seasoned professional”
The discussion started when “enthusiast” photographers are calling themselves professional because either:
• Their equipment is labelled “professional grade”
or
• High level of technical skill in photography. But not being paid for the work.
Another view – a professional is paid to do the work whereas hobbyist or enthusiasts who are not paid cannot be called professional even though their work might be better technically than the professional.
The Definition from the “free dictionary”
1. taking part in an activity, such as sport or music, as a means of livelihood
2. displaying a high level of competence or skill: a professional and polished performance
3. undertaken or performed by people who are paid: professional golf
The dictionary accepts that the professional can be paid or unpaid but has the necessary skills.
What are your views?
Michael "feng shui" Oon's Blog 
I work in an art gallery which mainly only shows the work of ‘professional’ artists. The boundaries are blurry.
One definition I have heard is that “a professional works at their craft when they may not really want to, whereas an amateur only works when they want to”.
Therefore discipline of application, facing and overcoming numerous difficulties results in work with a recognisable professional polish whereas the amateur’s accomplishment is more haphazard. Are the amateur’s professional-looking works just ‘lucky’ or does waiting for the right mood and moment bring the right conditions? In my experience the amateur (and their audience) are often disappointed with the results after the mood has struck because their aspirations lack the benefit of skill, knowledge and well-honed practice.