A professional is like a medical doctor, lawyer, accountant, or engineer. A professional has a professional designation administered by a government. A professional is legally responsible to the public. However, many Ph.d's are only administered by an academic institution but are certainly professional.
The SEC considers anyone who buys and sells securities as a business to be a Dealer which requires registration. Even the IRS trader-status seems to meet this definition. I can help them with the Dealer definition by saying that the definition of a Dealer should be someone who regularly buys securities at the bid and regularly sells securities at the ask.
Now the IRS trader-status requires that the trader continuously make trades. But someone could be an investing company, without registering as an Investment Company, by not being an issuer of their own securities. But this type of investing company could meet the definition of a Dealer ! An investing company that has a particular industry focus and that does not claim to be in the business of investing might get by without registering as a Dealer since the company is like a holding company. Or a hedge fund, as for any purpose, has 100 or fewer accredited investors and is not required to fully register as an Investment Company. I suppose that the hedge fund registers as an Investment Adviser.
A corporation that is an issuer can avoid being an inadvertent Investment Company by having investments that are 60% cash or Treasury securities. A corporation like that must have a core purpose other than investing and must not claim to be an investing company.
I capitalized Dealer, Investment Company, and Investment Adviser but those are not professional designations. I gave a link to Broker/Dealer but links to Investment Company and links to Investment Adviser can also be found.