What is the difference between a Distributed Ledger Technology and a Blockchain?


Hi it’s Keir Finlow-Bates here, and today
I’m gonna answer a question I was asked, which is what is the difference between
distributed ledger technology and blockchain, and actually I’m going to
answer in 3 different ways. So the first answer is an engineering answer, which is
let’s look at the terminology: a distributed ledger technology has to be
distributed, so it needs to run on different servers, it has to be a ledger
which is basically a data record that is immutable and cannot be changed, you
can only add updates and finally it’s a technology, and now that part doesn’t
really add very much because I doubt that there’s a distributed ledger art or
a distributed ledger humanity out there. So if we look at blockchain: blockchain
is distributed, so it satisfies the first term, and it’s a ledger because the
blockchain record is immutable. So what is the difference? Well from an
engineering point of view, blockchain is a subset of distributed ledger
technologies, because there are other systems that are distributed and contain
ledgers, but are not structured as a blockchain; namely blocks of data linked
together in a hash linked list. So that’s the engineering point of view, and an
example of a distributed ledger technology that’s not a blockchain would
be a DAG, or directed acyclic graph, although it actually gets a bit more
complicated because you could argue that a blockchain is a specific DAG, where the
edges are the links between the blocks and the vertices are the blocks of data
themselves. It’s like it’s a linear one dimensional graph that is
directed, so that probably didn’t clear things up immensely. So let’s move on to
the second answer which is a, I guess, a socio-political one – which is: what do the
various parties who use these terms want to do with the words.
Why would somebody refer to something as a DLT, rather than as a blockchain. And by
socio-political I mean for example the fact that feminists will point out that
we use certain words such as doctor and nurse in a way to set a social agenda.
Because you hear people refer to a female doctor or a male nurse but you
never hear people refer to a male doctor or a female nurse. These words in the
English language have historically been used in a gender specific way to the
detriment of women, unfortunately. So when you look at DLT and blockchain you’ll
find that there are certain sectors in society who are not very happy about the
first use case for blockchain, namely Bitcoin, and they talk about things like
“Blockchain not Bitcoin” or if they’re even more extreme they talk about “DLT
not Blockchain” and there it’s kind of trying to use words in order to push a
particular agenda and shift the dialogue away from one area to another. And I’m
guilty of that myself actually because in all the patents are filed in 2016, I
refer to distributed ledgers rather than to blockchain, because at that point
in particular the banking industries really didn’t like to use the word
“blockchain”. Now they seem to be happy to use it but they’re not happy to use the
word Bitcoin. So the third one is looking at DLT versus blockchain in a
linguistic game sense. If you’re serious academic you’ll be talking about the
later Wittgenstein way of looking at words, which, you know, is that they build a
meaning in a social context and if you’re a bit more whimsical you might
reference Humpty Dumpty out of Lewis Carroll’s Alice in Wonderland, where he
says “words mean what I intend them to mean, no more no less” and there you can
just look at: how are the words used in society. And in fact I think in general
blockchain is actually used as a shorthand nowadays
by most people to mean blockchain and distributed ledgers. It’s quicker to
get across the message what it is your conference is about if you say it’s a
“blockchain conference” – then the largest group of people understand what you mean
even if actually most of the conference is going to be discussing
multi-dimensional directed acyclic graphs, whereas if you say that you’re
having a DLT conference you’re gonna have a smaller audience who know what
you’re actually talking about. So there you go: three answers to what is the
difference between DLT and blockchain, and I think the summary really is that
blockchains are a subset of DLTs because DLTs also include DAGs and other
distributed immutable data stores, however for all practical intents, if you
say blockchain when you’re actually referring to something that isn’t
strictly a “I’m adding blocks of data at a regular interval to this chain”, people
will still know what you’re talking about.
I hope that clarifies things a bit – got a bit more long-winded than I intended.
I’ll see you in the next video soon. Bye for now! (Yay, no wind noise!)

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