Red Japanese maple, Acer palmatum var atropurpureum has red new growth only.
As the leaves harden, they begin to turn green or a bronze green, sometimes
dark purple green.

The so-called 'Atropurpureum' strain are generally seedlings, so they vary
widely. I have one that I picked out of a group. It is planted at the southwest
corner of the house, in Zone 5. It does get some shade in late afternoon. Mine
is dark red almost all season long. It does turn greenish around July-August,
but even then, the new leaves are red, so it is not that green. And before
long, it starts to get its autumn color, which is a different shade of red.
Even last summer, which was so incredibly hot, it held its red color, but some
of the leaf edges got scorched. And it is such a good grower, it is only about
5 years old, but I have to give it a major pruning, since it is in the
foundation planting. My 'Butterfly' survived our harsh winter with no problems.
But I notice the neighbor down the street lost her 'Crimson Queen.'
Iris,
Central NY, Zone 5a, Sunset Zone 40
"If we see light at the end of the tunnel, It's the light of the oncoming
train."
Robert Lowell (1917-1977)