These terms refer to movements of companies between the public sector and the private sector. When the State takes direct control of an enterprise, i.e. when it holds over 50% of its capital, we talk of nationalisation (cf. Law of 11/2/1982).
When the State loses direct control of an enterprise to the private sector, we talk of privatisation (cf. laws of 6/7/1986 and of 19/6/1993).
The acquisition or sale of all or part of the capital of (directly or indirectly owned) subsidiaries of public enterprises, causing public-sector enterprises to "enter" or "leave" the public sector, is known as "respiration".