No, “clinical study” and “clinical trial” are not necessarily synonymous in the context of non-interventional studies in the EU.

In general, a clinical study refers to any investigation involving human participants that is intended to discover or verify the clinical, pharmacological or other pharmacodynamic effects of one or more medicinal products, or to identify any adverse reactions to one or more medicinal products. This can include both (interventional) clinical trials and non-interventional studies.

A clinical trial, on the other hand, specifically refers to a type of interventional clinical study where one or more medicinal products are tested in human participants with the aim of evaluating their safety and/or efficacy i.e., there is a treatment intervention involving a medicinal product.

Non-interventional studies (NIS) are observational studies that do not involve any treatment interventions or protocol-dictated administration of a medicinal product. They are designed to observe patients in their natural clinical setting and collect data on the outcomes of a specific drug or treatment intervention.

So, while a clinical trial is a type of clinical study, not all clinical studies are clinical trials.
 
Revision 2 of ICH GCP caused confusion to those of us who work with non-interventional studies. The glossary claimed that a ‘clinical trial’ was synonymous with a ‘clinical study’ (Section 1.12 of ICH GCP(R2)). This works if you conduct clinical trials (they are a type of clinical study), but not if you conduct non-interventional studies, which are a type of ‘clinical study other than a clinical trial’ (Article 2.2(4) of Regulation EU/536/2014).
 
The (draft) Revision 3 of ICH GCP includes a new definition of ‘clinical trial’ provided in the Glossary, which removes any confusion regarding clinical trial vs clinical study.

Clinical Trial = Any interventional investigation in human participants intended to discover or verify the clinical, pharmacological and/or other pharmacodynamic effects of an investigational product(s); and/or to identify any adverse reactions to an investigational product(s); and/or to study absorption, distribution, metabolism and excretion of an investigational product(s) with the object of ascertaining its safety and/or efficacy.