Plan & manage an Azure AI solution ยท 25โ€“30%

Choose the right Foundry service & model

~3 min read

The platform in one picture

Service picker

TaskUse
Chat, content generation, reasoningFoundry Models (LLM deployment)
Agents (LLM + instructions + tools)Foundry Agent Service
Text analytics: entities, sentiment, summarization, PIIAzure Language
Speech to text / text to speech / live voiceAzure Speech
Text translationAzure Translator
Fields from invoices, receipts, formsAzure Document Intelligence
Multimodal extraction: docs + images + video + audioAzure Content Understanding
Vector / hybrid search, RAG retrievalAzure AI Search
Central knowledge for agentsFoundry IQ
If the question says “cost-effective, predictable, common task”, pick a Foundry Tool, not a generative model. If it says “generate original content / reason”, pick an LLM.

Model type picker

NeedModel typeExamples
Deep reasoning, complex generationLLMGPT-5, Mistral Large, Llama 70B
Speed + low cost + edge devicesSLMPhi-4, Llama 8B
Math / code / multi-step logic (built-in reasoning)Reasoning modelo-series, Claude Opus
Semantic search, RAG vectorsEmbedding modelAda, Cohere embed
Image from textImage genGPT-image-1
Video from textVideo genSora 2
Prompts that include imagesMultimodalGPT-4.1, GPT-4o
Audio โ†” textTTS / STTGPT-4o-tts, GPT-4o-transcribe
Chain-of-thought prompting = technique for non-reasoning models. Reasoning models do stepwise logic internally โ€” don’t prompt them to “think step by step”.

Benchmarks (model selection)

Benchmarks are standardized test scores shown on each model card so you can compare models before deploying one.

Retrieval & indexing choice

Search typeHow it matches
KeywordExact terms
VectorEmbedding similarity (cosine) โ€” meaning, not words
SemanticSemantic models re-rank meaning
HybridKeyword + vector + semantic โ€” recommended for gen-AI apps