In the vast majority of cases people do not know what a consultant is, and they associate it with a technical position, like an expert programmer or something like that.
If we look for a consultant, we will have several meanings, but in our case, we are left with the following:
Consultant: Person expert in a subject on which advises professionally
If we look at this definition, which also coincides with what we can find in wikipedia, we observe that it is not a position linked to technology, there are consultants of all subjects, of all tastes and of all colors.
But if we want to focus on business and technology consulting, there are usually two types of consultants, vertical consultants and horizontal consultants.
The vertical consultants or business consultants are those specialized in specific business, for example, in the food sector. And on the other hand, horizontal consultants are those experts in a specific technology, for example, Architectures in Mainframe.
This definition comes from the concept of vertical solutions and horizontal solutions, which define whether the product is applied to a specific business, or resolves a specific function of several sectors, such as a word processor.
The consultant, is not to go into detail, is to determine other aspects that a normal person would not look. But above all, a consultant is someone who gives a valid, judicious and justified answer to a question.