What is the key difference between `resources/read` and `resources/subscribe` in MCP?

In MCP, a **resource** is read-only data a server exposes, addressed by a URI like `file:///project/main.py`. Both methods in this question work on resources, so the difference is not about read versus write. `resources/read` is the simple one. The host sends a request naming a URI, the server returns the resource's current contents, and the exchange is over. It is a one-shot pull, like fetching a web page once. `resources/subscribe` is a standing request. The host tells the server, 'let me know whenever this resource changes.' The server then sends a notification each time the data updates. The host reacts by reading the fresh contents. So the axis is polling versus push. Read pulls the current state once. Subscribe sets up future pushes so the host learns about changes without asking again. The other options in the question, binary versus text or an approval difference, are not the real distinction.

Both methods act on the same read-only resource. The difference is one-shot pull versus standing push. `resources/read` is a synchronous one-shot fetch. The host sends the resource URI, the server returns its current contents, and the request completes. To see a later change, the host must call read again. That is polling. `resources/subscribe` registers interest in a resource. The server then sends a `notifications/resources/updated` message whenever that resource changes. The host reacts, usually by issuing a fresh read to get the new contents. That is server push. The practical payoff is latency and waste. For a live-updating resource, like a log file or a dashboard query, polling means repeated reads that mostly return unchanged data. Subscriptions let the host stay idle until the server signals a real change. The other answer choices are wrong. Both methods are read-only, so there is no write-side approval split. Subscriptions still flow as JSON-RPC notifications. Neither method is restricted to binary or text payloads.