what is the difference between worker and employee in belgium

Belgian labor law makes a difference between employee (white collar) and ouvrier (blue collar). The tendency during last years has however been to get rid of the differentiation, some changes are already done, some are on the prepare within the government. The biggest differences between the two are in trial and notice periods (shorter for blue collar workers), accrual of the annual holidays (mainly the payment practice of the paid holidays), salary guarantee during illness or other incapacity to work and conditions concerning the eligibility to unemployment benefits. More info here: http://www.belgium.be/fr/emploi/contrats_de_travail/types_de_contrats/na...
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In addition to this distinction different sectors and sometimes different type of employees/ouvriers have sectoral labor agreements (so called Commission Paritaires), which define in more detail the working conditions (f.ex. minimum salaries, working time, holiday accruals etc.). The indexation of salaries is also negotiated within these sectoral agreements. For some CPs the salaries are indexed annually directly in link with the consumer price index, for some the indexation is done only when the consumer prices change more than a set treshold. To know how and when your salary is indexed try searching with your Commission Paritaire number or ask from your labor union.