bert

A tidy fundamentals question that trips up anyone who only knows GPT. The signal is pairing each architecture to its task through its attention pattern, and explaining why the field settled on decoder-only even for tasks that are not generation. Here is that answer.

BERT and GPT diverge on one decision made before a single weight is trained: what does each token get to see? That choice ripples into attention, use case, and why one family now dominates. Here is the answer.