Ed Sheeran is currently in a civil trial over his song "Thinking Out Loud." The owner of the copyright to Marvin Gaye's 1973 hit "Let's Get It On" is suing Sheeran's claiming his song violated their rights under copyright law. Variety has a story here.
You can tell by the name of the plaintiff, Structured Asset Sales, LLC, that its main interest is in promoting a healthy, creative environment for musicians everywhere. (It is apparently somehow related to the heirs of Gaye's co-songwriter on the song, Ed Townsend.)
This video from Rick Beato breaks down a comparison between the two songs. The conclusion is that while the (rather simple) chord progression and groove of the verses are almost identical, the melody and lyrics of the verses are totally different. And "Thinking Out Loud" goes into a wholly different chorus.
What similarities there are between the two songs were not lost on Sheeran. Before the lawsuit, he performed "Thinking Out Loud," mashing it up with "Let's Get It On." But far from an admission of guilt, Sheeran said this is evidence that there was no intention to infringe on "Let's Get It On."
He testified, "If I had done what you're accusing me of doing, I'd be a quite an idiot to stand on a stage in front of 20,000 people and do that."
But a far worse case for copyright infringement of a Marvin Gaye song was recently won by the Marvin Gaye estate, when it successfully sued the writers of "Blurred Lines" for infringing on Gaye's 1977 hit "Got to Give It Up."
In that case, decided in 2018, the only significant similarity between the two songs seemed to be the feel of the "groove" – not the melody, lyrics nor even chord progression.
Rick Beato, again: