Summary of Differences between Level Up 5E and Original 5E

These are just some notes I took when trying to figure out the differences between Level Up Advanced 5E (A5E) and original D&D 5E (O5E).  They aren't necessarily complete or particularly organized, and I'll probably update this later.

1. Race has been divided into Heritage (biological) and Culture (where you were raised). 
2. Ability attribute bonuses are based upon your Background instead of either Heritage or Culture.  In O5E they were in race. This mostly means A5E characters should use A5E backgrounds and O5E characters should stick with O5E backgrounds.
   
3. Destiny  define your character's primary motivation and gives more structure to how to gain Inspiration and spend Inspiration.  There is also a Fulfillment Feature where you gain a special ability upon reaching your destiny.  Inspiration is also in O5E officially for good roleplay, particularly if it's not in a way advantageous to the party, but in practice DMs rarely grant it and all it often allows for is advantage.
4. Expertise is not just double your proficiency bonus.  Instead, it is a bonus die that starts at 1d4 and if you have stacking sources of expertise, they increase the die size.  There are more sources of expertise than in O5E.
   
1. Flanking is an optional rule in 5E.  In A5E, it's a default rule that grants expertise to the attack roll.
2. Characters get skill specialties that grant expertise (e.g. specializing in flattery grants expertise to Persuasion checks when appropriate)
   
5. Culture and Engineering are two new skills.
   
6. Classes are different.  Some of them have changed names, but even the ones that have the same name are different.
   
1. Monk -> Adept
2. Barbarian -> Berserker
3. Paladin -> Herald
   
4. Marshal is a 4E warlord
5. Rangers don't get spellcasting by default and have more exploration features than most classes.
   
7. In general, they wanted to make martial characters have more interesting options than just move and attack, so they all have maneuvers that require Exertion to use and a pool of Exertion that refreshes typically on short rests.  Think of them like martial spells.
8. It's also noted that martial classes are supposed to have more out of combat utility than they used to.
9. Exploration is a more emphasized pillar in A5E compared to O5E.
1. There are more rules about journeying and activities characters can take while doing so.
   
2. Food and water are abstracted away into Supplies.
3. Fatigue replaces Exhaustion.
4. If you gain more than 1 level of Fatigue, normal rest becomes insufficient to restore it and you need to find a Haven (known safe place) to get good rest to reduce Fatigue by 1 each long rest.
   
5. Strife is the mental equivalent to Fatigue.
   
10. Criticals
1. There are criticals with saves now
2. There are also criticals with ability checks
   
11. Combat
1. There are critical failures and successes with saves now.
2. When healed from 0 or fewer hit points, you gain a level of Fatigue.
3. Attacking from above gives you an expertise die.  (I have the higher ground!)
4. You can use a bonus action to fight "back-to-back" with an adjacent ally.  Your passive perception increases by 2 until start of your next turn or either of you move.  You cannot be flanked.
5. Dragging an ally uses your reaction and movement costs are tripled.  It still provokes attacks of opportunity.
6. Pulling from below -- if you are 5 feet below your target and not smaller than the target and you aren't grappled or restrained, gain an expertise die on strength checks and saving throws made against it.
7. Press the attack -- before you take the attack action, you can use a bonus action to designate one creature within your reach not already the target of a press the attack action.  Until the beginning of your next turn, melee attacks against that creature gain an expertise die, unless you have disadvantage.  Target can use its reaction to Fall Back.
8. There's Sprint in addition to Dash.  If you are unencumbered and not wearing heavy armor, speed quadruples.  If  encumbered, then triples.  Must be a straight line.  Can only sprint for number of turns equal to Con mod for free.  Otherwise, constitution (athletics) check with DC 10+ 1 per previous check.  Failure gains level of Fatigue.  This fatigue goes away after one minute of not sprinting.  You can't sprint if you have Fatigue.
9. Basic Maneuvers instead of making an attack: disarm, grapple, knockdown, overrun, or shove.
10. If you have the Extra Attack feature, the bonus action for an extra attack with the off-hand weapon allows for two attacks instead of just one.
11. Massive damage rules -- if you get knocked to 0 or below and the hit dealt 20 + 3xLvl or more damage, make a DC 15 con save or die instantly.  If you succeed, you get one level of Fatigue and Strife.
12. Taking damage when at 0 hit points can be an extra failed death save, level fatigue, or level of strife, attacker's choice (or just DM's choice if there is no attacker)
13. You can convert a critical hit against you into a normal hit at the cost of using your reaction and suffering one fatigue level.  Or sacrificing your shield.  Fatigue gained during the combat only takes effect after combat is over.
14. There's a Doomed condition where minor healing isn't sufficient to heal from imminent death.  7 or more levels of fatigue is one way to get Doomed.
    
12. There are rules for Strongholds as another way to spend your gold.  They always count as Havens.
    
13. There are rules for Followers.  They They feel more like contractors to me.  Another way to spend gold, 1-time fee.
14. Feats
1. There are new feats.  Some old feats have changed.  Some have been renamed.
2. There are multiclass feats.
   
3. There are feats that have prerequisites.
   
15. Spells
1. Just because a spell has the same name doesn't mean it's the same spell.  E.g. fireball has been nerfed to actually follow the spell power guidelines.  In O5E, it's actually overpowered due to its iconic status.
16. There's some rules for actions characters can take between adventures during their downtime, including training or modifying their spells.
17. There's an official Prestige system.