we can use Flash Player browser plug-in to play both FLV and SWF file;
Yes. From documentation for FLV:
[...] Flash Player can also play FLV files directly with MIME type video/x-flv. An FLV file encodes synchronized audio and video streams.
As for your other question:
FLV file contains only video/audio, but SWF file could contain not only video/audio but also other information (picture/animaton/etc.)
Yes. Again, I'd refer you back to the documentation:
The SWF file format delivers vector graphics, text, video, and sound over the Internet and is supported by Adobe® Flash® Player and Adobe AIR™ software. Flash Player already reaches over 98% of Internet-enabled desktops and more than 800 million handsets and mobile devices.
The SWF file format is designed to be an efficient binary delivery format, not a format for exchanging graphics between graphics editors.
Other questions:
One more questions, how to use Adobe Flash player manually?
What happens when you double click on a SWF file on your system? Typically, flash player standalone version should come up and play the SWF file. You have to figure out where the executable resides on your system.
Any ideas about how to make Adobe Flash Player play the flv file file so that I can have a try?
You can drag and drop your flv on the standalone player.