Telegram Bot HandbookTelegram API VS Bot API. What Is the Difference?
Basically, developing a bot means developing a program which connects to Telegram servers, receives some info (like incoming messages) and sends some instructions (like "reply to that message"). Let's dive into how it works.
MTProto API (also known as Telegram API) is the API through which your mobile or desktop Telegram apps connect to the Telegram servers. It is open, meaning that developers can use the API to create own Telegram apps.
It is named after MTProto encryption protocol which was specially developed by Telegram team.
Telegram Bot API is a different API that can only be used for bots. It is built on top of MTProto API.
Bot API was created to provide developers with a possibility of writing bots on plain HTTP-requests and not studying MTProto. In addition, Bot API has features to make development easier, such as webhooks and built-in HTML/Markdown markup.
However, you won't need this :)
You unlikely will write plain HTTP-requests: it is easier to use libraries instead. There are libraries for many programming languages and usually they have everything for convenient development.
So you can develop bots with either Telegram API or Bot API.
So which API to choose?
On the one hand, it is easier to pick a library written in Bot API.
On the other hand, Bot API is more limited. It forbids to upload large files by default or fetch old messages from chat history.
You can read about choosing the right library on the next page.
Functionality of Bot API vs Telegram API
| Feature | Bot API | Telegram API |
|---|---|---|
| Fetching messages | From updates only | From updates or by message IDs |
| Fetching users | From updates only | From updates, by message IDs (if the bot "saw" the user) or by username (200 times a day) |
| File sizes | ↓ 20 МБ, ↑ 50 МБ (Without local server) | Like regular users |
| Fetching group members | No | Yes |
| Get old updates | No | Yes |
| Run multiple programs with the same bot | Only if other programs use Telegram API | Yes |
Telegram API has a feature to get some updates. This may be useful to get a list of bot users if it was not saved or the database was lost.
Userbots
As Telegram API is open and has libraries that work with it, you can easily write a program that controls a user account rather than a bot.
Such programs are called userbots. There are userbots that put current time on the user's profile picture, collect messages from public groups and channels, and so on.
In general, userbots are useful to automate actions that users are allowed to do and bots aren't.
WARNING
Usually Telegram doesn't ban for userbots, but be careful. Telegram may limit or delete spammer accounts.