‘Survival’ is simply staying alive until rescued or the short term emergency is resolved. It’s term is hours to days, and a primary goal is to be found as soon as possible. You do not expect a survival situation and it cannot be predicted, although certain conditions can increase the odds. For instance, if you go hiking in the wilderness, your odds of getting lost or experiencing sudden weather shifts, or being injured without access to 911 are increased over sitting on your couch in front of the TV. Thus signalling equipment is of great importance, and having much of your equipment being shiny and/or bright colors is important. Your survival kit is an ‘insurance policy’. You don’t want to tie up a significant percentage of your funds in it or have to do extensive maintenance, and you should be able to carry it without any significant impact on your regular activities.
On the other hand, ‘Prepping’ for SHTF (fecal matter impacting the rotating ventilation device) or TEOTWAWKI (The End Of The World As We Know It) is long term; weeks to years and is largely based on AVOIDING other people. The ‘Rule of Threes’ can be amended by adding ‘3 seconds without preventing someone from murdering you or exposure to CBRN’. Signalling equipment is greatly reduced in importance, while defensive and personal protective equipment becomes much more important and concealment is key. Although these scenarios can occur unexpectedly due to external sources, often they are predictable if you have access to reliable news sources and common sense. You are replacing your current lifestyle with one which is completely different, so it can be costly and can (and should be) an ongoing process. And the quantity of stuff which will be useful pretty much exceeds what you can ‘carry on your back’, particularly under the conditions under which they become critical. Disaster resistant transportation and/or residence, and having stuff ‘stashed’ in appropriate places are concepts to consider. On the other hand, you want the ‘minimum requirements’ readily available in a practically transportable form; generally a reasonably sized and weighted backpack, for when you forced to go unexpected places on foot. This is sometimes known as a ‘Bug Out Bag’, or ‘BOB’.
‘Medical’ equipment and techniques become more important than ‘First Aid’ thinking (which is based on the concept that additional medical treatment will be forthcoming). Having resources which are renewable should be a focus. For instance, it would be silly to have seeds in a ‘Survival’ kit, but not having some in your Prepping supplies might be a bad mistake. A spare set of batteries might be adequate in your survival kit, but for long term power, you need solar/generator power sources and rechargeable batteries. Hunting and fishing skills and supplies, particularly those which don’t attract attention, will be of great benefit. Protection from chemicals, biological threats or radiation is likely to be of great importance, and personal hygiene should be a significant goal.
Although avoiding or protecting yourself from people who want to hurt you and/or take your stuff is a basic goal of Prepping, for the long term, a viable group can enhance your chances. ‘Primitive’ skills and the ability to evaluate and interrelate with other people will help you choose and be desirable to and accepted by a good group. Not only can a ‘community’ potentially survive better than a single person on their own, but can it can be a more enjoyable emotional environment as well.
As you can see, although both disciplines work to ensure that injuries are treated, exposure to the elements is minimized, and water and food are maintained at appropriate levels, the goals and time frames vary enough that these are actually different disciplines. Although they will have items in common, a survival kit is only of some benefit for SHTF/TEOTWAWKI events, and Prepping supplies are unlikely to be available if you experience a short term survival event.