What's the Diff? LTE VS. ISA
Once upon a time (about 12 years ago) in a land far far away (Annapolis, MD) lived an ogre (The MD Department of Natural Resources.) Ok, I'm just trying to make this story interesting.
When the DNR decided to regulate urban forestry in Maryland, it brought about the idea of making local professionals take a test to prove their competency in the field of tree care. The idea was that in order to legally work on trees larger than 20 feet in height, one would need to pass this test and pay the licensing fee. The local townspeople brought their pitchforks and torches to the town square meeting in protest (no, not really). But, many of the local tree guys were very upset as they were not really trained in arboriculture. So, for whatever reason (your guess is as good as mine), the DNR decided to hand out this license to whom ever ask for it!! Now, it is important to point out that this was a temporary "free pass" and the DNR did eventually start requiring that the test actually be taken.
What is the moral of this story? There are currently about 1200 licensed tree experts in the state of Maryland. Of those "Experts" there are hundreds (?? no one really knows??) that never took a test or had any formal training at all. You have no way of knowing if your "Tree Expert" actually has any training at all!!
That being said, a person that has taken the Maryland LTE test and has passed this test does possess the basic skills to perform tree work. However, the ISA (International Society of Arborists) has been researching and developing a knowledge base since the 70's that is unsurpassed by any private or government entities. In fact, a large portion of the Maryland LTE test is taken directly from, and used with permission, from the ISA test. It does not, however, encompass all the aspects of arboriculture nearly as well as the ISA arborist exam does.
So, in conclusion, check to see if your tree pro has taken the additional steps to acquire an ISA certification. An ISA certified arborist has up to date training on all aspects of tree care including: tree removals and tree trimming, integrated pest management (IPM), plant health care, hazard assessment, disease diagnosis and treatment, fertilization, stump grinding, lightning protection, cabling and bracing, aesthetic light placement and more.