Picts spoke Celtic, made Celtic art, lived Celtic lives, and did Celtic things. The Scots were an Irish people. Thus not Picts. They spoke a different tongue, but both are Celtic.
Yeah, the Scots conquered Scotland, but from other Celts. The Scots may not even be Celts, they didn't call themselves Celts, but we group them with similar groups in western Europe.
The modern Scots are as Anglo-Norman as the English though. Burns and co were full of .