Why can't (langchain) AzureOpenAI find a model that AzureChatOpenAI can?

Invoking a request using AzureChatOpenAI returns response as expected:

import os
from dotenv import load_dotenv
from langchain_openai import AzureChatOpenAI

load_dotenv()

llm = AzureChatOpenAI(
    azure_endpoint=os.getenv("AZURE_ENDPOINT"),
    api_key=os.getenv("TOOL_KEY"),
    api_version=os.getenv("API_VERSION"),
    model="gpt-4o-2024-08-06"
)

response = llm.invoke("what is 2+3?")
print(response.content)

Returns:

2 + 3 equals 5.

But using the same config doesn't work with AzureOpenAI:

import os
from dotenv import load_dotenv
from langchain_openai import AzureOpenAI

load_dotenv()

llm = AzureOpenAI(
    azure_endpoint=os.getenv("AZURE_ENDPOINT"),
    api_key=os.getenv("TOOL_KEY"),
    api_version=os.getenv("API_VERSION"),
    model="gpt-4o-2024-08-06"
)

response = llm.invoke("what is 2+3?")
print(response.content)

Returns error:

openai.NotFoundError: Error code: 404 - {'detail': 'Not Found'}

What am I missing here?

AzureChatOpenAI supports chat completion models, including newer models like gpt-4o-2024-08-06. AzureOpenAI supports text completion models, but NOT chat completion models (like the new gpt-4 models). If you want to use gpt-4 models, stick with AzureChatOpenAI.

More info here, and in the top banner: