What is the difference between mediation and advertising?

Question

Law in IT

I want to register as a self-employed person and provide marketing and advertising services, according to the law, this activity is allowed for a self-employed person. But a self-employed person cannot engage in intermediary activities!

What is the difference and where is the boundary between these definitions?

Example, Vasya contacted me and ordered advertising services, but Vasya does not have money for advertising, so we agreed that upon receiving an order for 1000 rubles, 25% of the order from will pay me for advertising services.

Is this promotional activity? But what is mediation?

Intermediary services - a form of entrepreneurial activity, which consists in facilitating the establishment of relations between producers and consumers in order to speed up and facilitate the circulation of raw materials, materials, products, money, currency, information ...

Those. in fact, I contribute to the establishment of relations between the Customer and Vasya.

Let's complicate the example, let's say Vasya is a house painter. Petya and Kolya also turned to me for services, they are also painters.
In order not to create competition for myself, I place one ad and drive it to the landing. Now I have a lead that I sell to Vasya, Petya and Kolya (let's say I sell randomly). Is this an intermediary activity or advertising?

A lead is a product of my activity, i.e. I get it doing advertising.
Or a lead - a potential client who wants to receive services that I myself do not provide, but am an intermediary?