I find the oed note puzzling, because the oed2 (and oed3β€”there was no change) article gives the pronunciation of ate as /eΙͺt/ /Ι›t/ /iːt/ and also makes it clear that /eΙͺt/ is the older form,. In short, what is the difference between the following sentences? I did eat my lunch an hour ago.

They both are past tense. Honestly, i'm confused between them.