(in progress)
Burrow is a permissioned ledger and can be used in a private or public context. Read more about permissioned ledgers - Monax.io
Merkle tree is a hash-based data structure that is a generalization of the hash list. It is a tree structure in which each leaf node is a hash of a block of data, and each non-leaf node is a hash of its children. Typically, Merkle trees have a branching factor of 2, meaning that each node has up to 2 children. From/read more about Merkle trees - brilliant.org
Tendermint is a consensus engine that can be used in a private or public context. Read more about Tendermint