As I recall there are some important differences between LPC and LambdaMOO. More philosophical differences showing the background of the people who worked on them. Original LambdaMOO inspiration from the TinyM* world (if I vaguely recall Stephen White aka ghond the original MOO author came out of that community) plus was worked on by some Lisp and Smalltalk/Self inspired people (Pavel Curtis the maintainer worked at Xerox PARC and one of the key authors/wizard yduJ/Judy had some Lisp background if I recall) -- while the background with LPMUD was more RPG/gaming oriented.
LPMUD/LPC worked on editing class files and compiling them, while in LambdaMOO you edited your objects and verbs right in the environment. LambdaMOO had an object database and code was part of the database, while in LPMUD the code itself was in a separate filesystem. As an analogy: LambdaMOO was more like Smalltalk (live editing objects inside an image/object database) while LPMUD was more like editing a filesystem you dynamically recompiled. Now I believe LPMUD had an editor etc. right in the environment but you were editing a filesystem, not the objects themselves.
LambdaMOO was prototype oriented not class-based, so encouraged a lot more one-off authoring without messing up class hierarchies and the like. You could just dynamically throw together a new thing by parenting from an old thing and adding methods and props right on it and then later you could formalize that into something other people could use. Or not.
If I recall LPC didn't have the same kind of granular permissions system that MOO did and so there was more restrictions on who was allowed to program and who not. There was little risk in giving a MOO user a "programmer bit" on LambdaMOO as the environment was very sandboxed and capable of handling lots of amateurish programmers without stepping on each other. "Wizards" had the ability to modify shared common prototypes, but people who were "just" programmers could run off and create their own things and other people could borrow from them, etc. I suspect most LambdaMOO users ended up as programmers.
I think the LPMUD model makes more sense for building a game and iterating on it. LambdaMOO was about a shared authoring environment where people built things all day long (and chatted) rather than played a game.
Finally, LPC (or dialects of it...) I believe executed quite a bit faster than LambdaMOO. So much so that I believe at one point some people I knew of actually wrote a LambdaMOO compiler/environment in LPC -- maybe the DGD driver? -- and it outperformed LambdaMOO itself.