Is the phrase "por tanto" equal to "por lo tanto"
I googled the meaning of "por tanto" yesterday, and I found there is another phrase "por lo tanto", I don't think the meanings of both phrases are the same. However some people said they represent the same meaning "therefore", on the other hand, some people said:
por tanto = in regard to, regarding that...
por lo tanto = therefore
But it dosen't make sense, since I couldn't connect the 2 meanings with the article I read.
The article I read about "por tanto" as below:
El número de personas que hablan español en el mundo es de unos 450 millones. El español, por tanto, la tercera lengua más hablanda del planeta, después del chino mandarín y del inglés, y la segunda lengua más internacional.
Could someone tell me what are the real meanings of both phrases, and how to translate "por tanto" in this article? Thank you very much!!!