E is when you get paid when you do your job, usually within a fix amount of time or a pre-determined achievement list. The good thing is your income is relatively consistent. If you are the 9-5 type worker, even if you go to work and surf the net the whole day, you still get paid that day !!
S is when you think you are doing a business but actually you are not. Basically you are still selling your time and effort in a linear way. At the moment you cut down your time or your effort, your income drops accordingly. The good thing is if you are a very hard working person, you are mostly likely to earn a lot.
B is when you have an idea and you get other people to make that happen. You are Managing it but you are NOT Doing it. Significant differences between S and B is that B is operated within a well established "system" while in S, you are the system itself.
I is when you keep your money in FD and every month your money increases.
May be he did but not emphasized enough.
For example, a worker who goes to work everyday, just do whatever asked to do and waiting for month end paycheck falls under E.
However, if another worker is expanding his personal network during his career in order to move up the rank and also join better bigger companies could be considered as S. He could be treating his employers as his customers, whom he pleases the customers in order to get paid higher and higher.
E worker works from 9 to 5, selling time for money. S worker may not appear in office all the time but his mind is definitely 24 hours online thinking how to expand his 'business'. Most CEOs operate their jobs like a Self Employed business.
Beggar who beg 9 to 5 can be considered doing a 'job' as E. Beggar who analysed what places to be at what time to maximize his 'income' could be a S. Beggar who gather other beggars to learn his begging strategy while he no longer go out to beg but share a commision of what other beggars have beg could be a B.
So wherever you are whatever you are doing now, you can do it the E way, the S way or B and I ways. Its a matter of HOW you earn your income, NOT what you do.
One more heads up ... I also think Robert miss out one very important category. There are a total of 5 income category types, not just 4.