What does “+-” mean in algebraic notation?
This symbol means "White has decisive advantage", which means that White's advantage is big enough to secure him victory. As for symbol -+ it means "Black has decisive advantage".
What does this notation mean?
This notation is introduced to bypass the language barrier so any reader ( Japanese, English, Arabian, Marsian, it doesn't matter! ) can understand the comment behind the move. In the old days before this notation, commentaries were given in words, which required the reader to know commentator's native tongue or to find the translation of those commentaries. This way, when commentator writes +- behind the move, everybody ( Japanese, English, Arabian, Marsian, it doesn't matter! ) know what it means. It is shorter and cleaner this way.
Is it standard?
Yes, it is. The symbols were invented by Chess Informant and accepted as a standard. You can find out more about chess notation here and you can find the complete list of symbols here.
And why are the two games using it with the symbols in different order?
Because the positions in those games are different -> in one White has the decisive advantage while in the other it is Black who should win.
Hopefully this answer helped you. If you need further clarifications leave a comment. Best regards.