The subscription package (Adobe CC) has you pay a monthly fee, typically $9.99 for the photography package, and you retain a license as long as your subscribe.
- Advantages:
Access to latest versions of Lightroom & Photoshop all the time, automatic update when a new version is released, a few additional programs and apps, cancel at any time if you don't want to use it.
- Disadvantages:
Need an internet connection occasionally to verify license (may be inconvenient if you're traveling somewhere w/o internet), you don't permanently own the software, continue to pay monthly fees regardless if you use the new updates or regardless if your total subscription cost has exceeded the value of the standalone software.
The standalone Lightroom software, version 6 now, is a traditional buy and own software copy. The actual software program, today, is the same for Lightroom 6 and Lightroom CC, it's just the licensing that is different.
- Advantages:
You own it outright and can access the software any time, only pay once vs monthly, don't continue paying a subscription fee that eventually exceeds the cost of the software, don't have to upgrade if you don't need the latest software features on new versions.
- Disadvantages:
Miss out on having access to both Photoshop & Lightroom for more advanced/detailed edits, miss out on always having the latest upgrade version of the software, upfront cost is larger
I bought the standalone software for my purposes - I picked it up when it was on sale and CC was just coming out, and it cost less than a year of the subscription package. I own LR5 since I didn't see much advantage to the upgrades in LR6 (I use separate software for panoramas and HDR, and they're pretty easy to interface with and export/import with LR). If they improve the HDR engine or have some larger upgrades in version 7, then I'll consider the software upgrade at that time. If I had an Adobe CC subscription, I would get that upgrade automatically; however, that's probably the biggest factor that you need to determine for your needs when choosing between the two options.
Occasionally the CC subscription goes on sale too for a 1-2 year commitment, so it can even out if you need to have the latest and greatest versions. I can do 90-95% of what I want to edit within Lightroom on its own, but there have been several occasions where I've wanted access to Photoshop for more detailed edits that you just can't accomplish in LR alone.