You have the Capitalist and the Worker,
A Capitalist (Bourgeoisie in Marx's writings) is someone who makes money primarily with money (or Capital).
A Worker (proletariat in Marx's writings) is someone who makes money entirely with Labor
Then you have the small buisinessman or self employed (petit-Bourgeoisie in Marx's writings) who has Capital but also creates value with labor, for example a plumber with his own truck and tools, or a barber shop where the boss is a barber.
(there are others but we'll keep it simple.)
There are other valid was to look at class, but Marx used this way as a way to analyse a part of economy.
Capitalists can be (broadly speaking):
Industrial Capitalists: Capitalists who produce commodities (goods and services) for consumption, anything from engineering firms, to factories to software producers to costumer support to massage parlors to landscaping. These are Capitalists in productive industries.
Financial Capitalists: Capitalists who lend Capital, Bankers, Financial institutions, Brokers and so on, these are non productive industries but many times necessary for the function of productive industries.
Merchant Capitalists: Capitalists who buy and sell commodities, Stores, wholesale, import export companies and so on, like financial Capitalists they are non productive but many times necessary for the function of productive industries.
(Again, we'll keep it simple and leave it there.)
Amung Workers you have productive and non productive
Productive: Anyone invovlved with creating commodities, be it a product or a service, engineers, factory workers, garderners, barbers, software engineers and so on.
Non Productive: People involved with paid activities that are necessary for functioning of hte productive industry: Security guards, accountants, managers, HR, advertising and so on.
Obviously these are roughs and sometimes you have crossovers, however using this analysis will allow you to understand production in capitalism.