Why they sound alike
Coldplay's Hymn for the Weekend (released January 25, 2016) has a similar groove, verse vocal melody, and verse chord progression (relatively speaking) as Groove Theory's mid-90's chart-topper Tell Me (released September 5, 1995). Hymn for the Weekend's chorus vocal melody is also reminiscent of the intro vocal melody to fun's We Are Young, and Fabolous' Throw It In The Bag. Compare the melodies for the lines "[So if by the] time the bar closes and you feel like falling down" with "I-Oh-I-Oh/Got me feeling drunk and high.",
Hymn for the Weekend (:44) VS Tell Me (:21) [verse vocal melody and groove],
Hymn for the Weekend (1:48) VS , [chorus vocal melody],
Hymn for the Weekend (1:48) VS
