Complex sentence: The Thouron Prize is sometimes seen as the sophomore/junior analog of the Rhodes or Marshall Scholarships, which can be applied to only during one's senior year and which typically cover two years of graduate study rather than one undergraduate summer.
Split into simpler sentences: The Thouron Prize is sometimes seen as the sophomore/junior analog of the Rhodes or Marshall Scholarships. The latter can only be applied to during one's senior year and typically cover two years of graduate study rather than one undergraduate summer.