(USD unless otherwise specified)
A subscription service is where you pay a monthly fee to have full access to a complete library of karaoke tracks (typically mp3g). After paying the fee you can download any number of tracks from the library for your use, but you aren't able to keep them. Typically, subscriptions are proprietary to the software you use and as soon as your subscription ends, you no longer have access to any of the tracks you downloaded.
Not everyone will want a subscription service, whether you do or not should be the first decision you make before you buy your karaoke software. Subscription services are great for karaoke hosts who are just starting out because it enables them to get a professional range of good quality tracks for their singers without having to outlay thousands in track purchases.
If you wish to use a subscription service, now or in the future, your second decision before you buy any karaoke software, should be choosing software that uses your subscription of choice, because, depending on the software you buy, you will be locked into only having that manufacturers subscription service as an option. Prices and performances vary a lot, so make sure your subscription service is going to meet your needs before buying your karaoke software.
A download service is a service where you pay for and own downloaded karaoke tracks.
Download services are often a part of modern software and can be a way of purchasing karaoke tracks from within your karaoke software offering unsurpassed convenience. When choosing your karaoke software player, the seamless download service may or may not be a prime consideration in your choice of software depending on how important convenience is. Download services are also available independently, simply download songs into your library and then play them with your software player of choice.
Imagine you're hosting a public show and a singer asks for a song that you're not sure if you have or not. Simply type the title into the software which advises that you don't possess it yet but offers to download it for you whilst you continue hosting other singers. Your singer walks away happy and it takes you the smallest amount of time to get it. This is as convenient as it gets for obtaining new songs.
Of course singers often get used to a particular version of their song and may not like the brand of song that your download service provides. Not all download services are part of software and getting the right brand at the best price often means going somewhere other than the proprietary service running with your software. Note that not all karaoke software has a download service yet most pro - karaoke software players will play the most common format (mp3g).
Proprietary download services tend to be more expensive than non-proprietary services, but you can still use tracks from non-proprietary services.