The differences that mark a dissertation and a thesis may be subtle but not entirely indistinguishable. There are some clear-cut parameters that set apart thesis and dissertation like length, presentation, format etc. The difference between a Thesis and Dissertation is also made confusing by different universities.

1. Difference between dissertation writing and thesis writing
The differences that mark a dissertation and a thesis may be subtle but not
entirely indistinguishable.
There are some clear-cut
parameters that set apart
thesis and dissertation like
length, presentation, format
etc. The difference
between a Thesis and
Dissertation is also made
confusing by different
universities. Most
universities in North America
call a PhD research paper a
dissertation and the masters
degree research paper a
thesis. But most British
universities call the PhD the
thesis and the masters the dissertation.
Dissertation writing is a lengthy formal treatise compulsively required for
obtaining a doctoral degree in any university. A is also a treatise but for the limited
purpose of validating a hypothetical proposition as a result of research findings. A
thesis has to be submitted for obtaining an advanced academic degree.
A dissertation is generally written at the end of one’s research degree studies and it
should reflect an erudite and in-depth knowledge of a topic. The dissertation has to
be inevitably long and more specific. A thesis will be shorter and will not cover as
much of details as a dissertation.
The length of a thesis and dissertation are invariably set by the concerned
university departments or faculties based on the nature of subject, its scope and
type of presentation. Dissertation in the humanities and social sciences are hover
around 100,000 words. Thesis in the sciences is generally set at roughly half that
length. The length of master's thesis varies considerably, but is almost always
between 10,000 and 30,000 words. In most cases, a thesis is shorter than a
dissertation. This vindicates the fact that a Master's thesis is usually written in a
relatively brief period of time – mostly under a year, whereas a PhD dissertation
takes much longer.
A thesis written for a Master’s degree usually involves analysis or synthesis of data
and researched contents based on the interpretation of the person submitting the
thesis. It is also permitted for a Master's thesis to rely on the research of other
writers and scholars. But a PhD dissertation is written more in the form of a book
than a formal research paper and calls for findings based on firsthand original
research.
The difference between a thesis and dissertation can be summarized as:

2. • In most universities, a thesis is written to get master’s degree while a
dissertation is written to get doctoral degree.
• The length of thesis is around 100+ pages for dissertation around 300+
pages.
• A dissertation is much longer than a thesis as it has much more
detailed information in terms of researched data, diagrams, fact and
figures.
• A dissertation has to reflect original research, theory or argumentation.
• A thesis has study of data and borrowed ideas from other scholars.
• A thesis is usually completed in a year since it is written less number of
pages than a dissertation.
• A dissertation requires much more time than a thesis since it has a
greater number of pages and it requires original research and in-depth
analysis.
Whether it is a thesis or a dissertation, it is important to clearly explain your
argument substantiated by valid logic and reasoning. The goal should be to
communicate facts to the reader cogently and in an unambiguous manner.
Most of all, remember that you need not feel diffident when you undertake to write a
thesis or dissertation. There are plenty of tutorials available, both online and
offline and more importantly, your professors and advisors will be only too ready to
offer you help in any manner you need.
Source: http://www.doctortext.com/