what is different between them? by manual, i can choose which blog post to comment,right? but by software , i also can choose. i am confused why so many ppl say blog comment tool is crap.
It's crap because bloggers that actually have the type of blog that can "benefit you" aren't letting some idiotic comment in.
There is a BIG difference between a software and manual process.. If you use software on blog commenting, they will suspect you as an spam. But in manual, you are always safe. Just a tips when doing SEO, try to always avoid those softwares.
In most cases when using software the comments are very short, does not go along great with the topic at hand etc. thus most people can tell it is junk. Manually submitting you can respond back and make your post part of the topic, however you can still spam this way as well it just takes longer.