Is a theory the same as a hypothesis? 
“Any physical theory is always provisional, in the sense that it is
  only a hypothesis: you can never prove it.”
Excerpt from Stephen Hawking, A Brief History of Time, iBooks.

So does that mean that Theory = Hypothesis?
 A: The sentence, as it is quoted, seems moot to me.
In fact, it would apply to any logic theory: a logic theory is nothing else that a collection of statements assumed to be true (axioms/hypotheses - the name is not so important), and a collection of logic symbols and rules of inference (also assumed to be true) that codify how you can get new true sentences combining true sentences.
Given that, it is then the role of physics that differs e.g. from the role of mathematics: the former aims to use axioms/hypotheses and rules of inference (sometimes only intuitively) to produce predictions, and to verify these predictions (and in turn hypotheses) by experimental observation; the latter aims to prove non-trivial true statements, using in a rigorous and strict fashion the axioms and rules of inference.
My personal definitions of hypothesis and physical theory would then be the following:


*

*An hypothesis is a statement assumed to be true.

*A physical theory is a logic apparatus built (with a "physical" level of rigour) on hypotheses, that provides a relevant number of testable predictions, that can either support or contradict the physical relevance of the aforementioned hypotheses.
In any case, contrarily to what happens in mathematics, there is no precise and agreed definition of physical theory. However if you also take a look at the ones given in the comments, they have more or less the same spirit as the one above.
A: In a strict true/false sense, every scientific statement is false. For example, the following two statemaents are both false:


*

*The Earth is flat.

*The Earth is a sphere.


However, the second statement is much closer to the truth than the first. [1] It is this kind of closeness to truth that distinguishes a scientific hypothesis from a scientific theory. In one sense, both hypotheses and theories are unprovable statements that are backed by limited quantities of evidence. There are many related ways to distinguish between them:


*

*Hypotheses have some evidence backing them; theories have a lot.

*Hypotheses can explain one set of data; theories can explain a wide variety of data.

*Hypotheses explain all currently known observations and experiments; theories can predict the results of future observations and experiments.


Like anything that interacts with reality, there is uncertainty, interpretation, and shades of grey. Ultimately though, a hard line demarcating hypotheses and theories is not that useful. Just remember that every statement made by a scientist is followed by an unspoken, "but I could be wrong," and you'll be fine.
[1] Isaac Asimov, The Relativity of Wrong: http://chem.tufts.edu/answersinscience/relativityofwrong.htm
A: I would not agree that a theory is the same as a hypothesis. Rather I would argue that hypotheses are formulated within the framework a theory. Theory refers to the whole body of knowledge, usually driven by observations. The statements of a theory are validated by empirical data. Theory provides names and concepts for the observations so that scientists know what they are talking about. (NB some authors, most famously Quine, would argue that the statements of a theory are all on the same level, but that is not custom in everyday science)
A hypothesis is a mere statement, using the terms of a theory, awaiting experimental (or even theoretical) validation or falsification. 
Consider also the encyclopedic definition of the terms:
"A hypothesis [...] is a proposed explanation for a phenomenon." [https://en.wikipedia.org/wiki/Hypothesis]
"A scientific theory is a well-substantiated explanation of some aspect of the natural world that is acquired through the scientific method and repeatedly tested and confirmed through observation and experimentation." [https://en.wikipedia.org/wiki/Scientific_theory]
Hawking's point might have been that the scientific knowledge cannot be proven to be true. In this aspect, science is different from mathematics, metaphysics, and formal logic. 
