Your needs will dictate what type of score to look for, such as:
Full/Orchestral/Conductor's Score: Provides notation for all of the instruments and/or voices in an ensemble; parts are arranged in "score order;" conductor's scores are generally the largest and are for use by conductors in a performanc. The larger print enables the conductor to easily read all of the parts.
Study Score/Miniature Score: Full scores of a reduced size or print; usually 25 cm. high (or less); designed to be used for study and analysis rather than for performance. These are shelved separately and include MINI in the call number.
Score and Parts: An edition of a musical work composed for chamber or larger ensemble (e.g., string quintet, symphony, jazz ensemble, wind ensemble) which includes both a full or miniature score and parts for all of the instruments. The Music Curriculum Library maintains a collection performance materials; contact them directly because their catalog is not part of BU Libraries search and is not online.
Piano Reduction: Music originally for orchestra or some larger ensemble that has been reduced so that it can be played by a keyboard instrument; often concertos are printed in this format with an accompanying part for the solo instrument.
Piano-Vocal Score/Vocal Score: Scores of large works (e.g., oratorios, operas, etc.) originally composed for voice and/or chorus and instrumental ensemble which have the instrumental parts reduced for keyboard accompaniment. Such scores are often used for teaching purposes, rehearsals, and auditions.
Please ask for help in finding the right score for your needs.