彼は昔と比べるとまるで別人のようだ。

Meaning
he seems to be a different person compared to the past

Vocab used in this sentence

he, his, him, boyfriend
a, the, is, am, are, will
old, the past, once upon a time, long ago, former, formerly, ancient times
and, with, if
比べる
compare, differ, balance, contrast, relate, calibrate, collate
and, with, if
まるで
as, as if, it's like, just like
別人
different person, someone else, changed man, ngmoco, another person
to, of
よう
like, way, kind, so that, such as, manner
is, be, are, am, it is, seems

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