tl;dr: No, they aren't. Petitions to the UK government are a very weak political instrument anyway.
Petitions to the UK parliament are handled by the petition committee which are members of the UK parliament.
The official way to hand in an online petition is through the petition portal of the UK parliament. The promise of a response for 10,000 signatures and being considered for debate at 100,000 signatures only applies to this medium. But:
- Reaching the required number of signatures is not a guarantee that your petition will be discussed in parliament. It merely will be considered by the petition committee to be put up for debate. The petition committee is free to ignore any petitions they don't like. So your online petition can be ignored in any case.
- When you use a different platform and reach a high number of signatures, it is usually an obvious sign that there is public interest in an issue. That means it is likely important enough that it will get attention by the parliament committee which is actually responsible for it.
Also, keep in mind that a debate about a petition in the parliament is just that: a debate. It does not mean there will be a vote if the petition will be made a law. Online petition written by political laypeople rarely fulfill the formal requirements for an actual bill anyway.
All the parliament debate could achieve is inspire MPs to draft an actual bill based around the general idea of the petition which then goes through the normal process... if anyone feels like doing that.