It's interesting-- you've stumbled across what's actually a somewhat in-depth topic. Your question seems to pertain to the difference between corporate espionage vs. competitive intelligence. Both practices have the same end-goal: to acquiring knowledge about a competitor that can be used to make your own business more successful. The key difference is how this knowledge is gathered.
In competitive intelligence, one gathers information through overt means. This could include things like speaking directly to a competitor without concealing your identity and purpose, web searches, and paying for & using a competitors product through legal means.
In corporate espionage, one gathers information through covert means. This means like speaking to a competitor in the guise of a customer or existing client, hacking into company networks or databases, or violating a TOS agreement or contract to use a competitor's software.
Something to keep in mind is that governments are increasingly cracking down on people faking personal information online for the purpose of personal or professional gain. Depending on where you live, how it's used, and where the target of your research/activity is located, assuming a covert identity online (and getting caught) could lead to criminal charges, fines, and possibly imprisonment.
Additionally, there are a whole host of ethical concerns surrounding legal corporate espionage that muddy the waters even further.
For all of these reasons, I stay as far away from anything that might be considered illegal or unethical as possible. When conducting research on competitors, I always follow a few set rules:
1.) Always state your name, position, employer (or academic institution), and intent when speaking directly with a competitor for the purpose of intelligence gathering.
2.) If speaking directly with a competitor, ensure that person is authorized to discuss the subject.
3.) If a company offers free service/software, ensure that your use of such for the purpose of gathering intelligence does not violate their TOS.
4.) If the company offers a paid service/software, always pay, and never register accounts under false names, email addresses, or other fraudulent information.
I hope that helps point you in the right direction!