Explain Transformer and Fine-Tuning Basics

You're in an interview for an engineering internship centered on AI. Address the following:

1. How does a transformer model differ from an embedding model? Cover what each outputs, how each is typically trained, and the situations where you would pick one over the other.
2. How do pretraining and fine-tuning differ? Discuss why pretraining helps, what gets updated during fine-tuning, and which trade-offs or failure modes to keep an eye on. Overview: This item assesses knowledge of transformer architectures, embedding models, and transfer-learning ideas like pretraining and fine-tuning, checking ability in representation learning and model adaptation.