Legally speaking, both SAS and SARL companies are private limited liability companies. However, a SAS company is more flexible in terms of its articles of association than a SARL company, which makes it ideal for public companies.
However, the registration of a SAS company requires a capital verification, which makes the pre-registration process more cumbersome, whereas the registration of a SARL company does not.
However, the French tax office levies an annual social security tax on shareholders holding 51% or more of the shares of a SARL company (see above for a description of the types of SARL companies and how to avoid paying the social security tax), whereas a SAS company is not subject to the social security tax even if there is only one shareholder holding the shares of the company.