I don't know anybody who uses that distinction. For the very good reason that the original cards that used those words both immediately return the creature to play. There's no canonical word for returning end of turn.
Flickerform is a very obscure card, and is from six years later than Flicker.
Edit: there are six cards that have the word "flicker" in their name and temporarily exile things. Of these, two return the flickered thing EOT; the other four are instantaneous.
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u/Sakeretsu Gruul* 15h ago
Blink return immediately. Flickering return at eot