A method able to detect a possible common structure between two (or more than two) groups of curves is considered. This technique is part of the recent developments within the field of Functional Data Analysis. It is discussed how the standard approach based on factorial analysis for comparing groups of multivariate data can be used in this infinite-dimensional framework. The potentiality of such a functional method in terms of application is illustrated through a spectrometric functional data set coming from food industry quality control.