I have 5 sitemaps for one of my site.
Is there any difference between submitting those 5 sitemaps one by one to google vs creating and submitting just one site map which include those 5 sitemaps?
This URL has a perfect answer: https://www.sitemaps.org/protocol.html
...each Sitemap file that you provide must have no more than 50,000 URLs and must be no larger than 50MB (52,428,800 bytes). If you would like, you may compress your Sitemap files using gzip to reduce your bandwidth requirement; however the sitemap file once uncompressed must be no larger than 50MB. If you want to list more than 50,000 URLs, you must create multiple Sitemap files.
So if you have a site with say 50 URLs, then one sitemap file by itself is perfect. If however you have 100,000 URLs, then you're better off categorizing those URLs and making a sitemap file per category, then make a sitemap index file which lists those individual sitemap files.
Just go to https://www.sitemaps.org/protocol.html#index for details on how to make an index file.
Also, when sending sitemaps to google, send just the sitemap index file if you have one, and google will crawl it along with the sitemap files listed in the index file. If you don't want to make a sitemap index file, then make one sitemap file that lists all URLs for your site and only send that to google.