Relationship to the EIA Directive
The most significant difference between the EIA and SEA Directives lies in their scope: while an EIA focuses on a specific project (for instance, the construction of a railway or a highway or the establishment of an industrial installation) and on the environmental consequences/impacts of that project only, an SEA applies a more general approach when looking at public plans and programmes from a variety of sectors (agriculture, forestry, fisheries, energy, industry, land use planning, etc.) Such plans and programmes, by their nature and definition, stand at a higher level of planning and comprise of at least two (but rather more) projects that would fall under the scope of the EIA Directive. For instance, the transport infrastructure development programme of a Member State may include the construction of several railways and/or highways, while an energy strategy may include a large variety of projects both from Annexes I (large thermal power plants, oil and gas pipelines, underground gas storage or nuclear facilities, overhead cables) and II (smaller thermal power plants, hydropower plants, etc.) of the EIA Directive.
The CJEU, when clarifying the relationship between the two Directives, has also come to the conclusion that as assessments carried out pursuant to the EIA and SEA Directives, respectively, differ for a number of reasons, it is necessary to comply with the requirements of both of those Directives concurrently (Case C-295/10, Valciukiene and Others, para. 60).
Article 3 of the SEA Directive also recognises the strong interlinkage between the two Directives related to environmental assessments by requiring a mandatory SEA for plans and programmes “which set the framework for future development consent of projects listed in Annexes I and II to Directive 85/337/EEC”.