"professions' and "occupations" difference
"Transborder activities and the general dynamics that they produce can be performed by socioeconomic categories, such as professions, occupations, or classes,"
occupation --> to occupy ones time i.e. seamstress or blacksmith
profession --> publicly declared and certified occupation i.e. master blacksmith or master seamstress
References from the OSX dictionary
profession |prəˈfeSHən| noun 1 a paid occupation, esp. one that involves prolonged training and a formal qualification:
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occupation |ˌäkyəˈpāSHən| noun 1 a job or profession: 2 the action, state, or period of occupying or being occupied by military force:
The sentence isn't very well written, but since it isn't yours (I presume), you can't revise it. To answer your question, the difference is largely one of education. "Professions" are followed by people with academic qualifications: doctors, lawyers, accountants, engineers, etc. "Occupations" are done by unqualified or semi-qualified people, such as traders, manual labourers, factory workers, drivers.