In concept of usability ,What is the difference between user's perspective vs perception?
The user's perception is shaped by their perspective.
What they see depends upon the viewpoint they see it from.
How useful something is to a user depends upon what they want to use it for.
How usable something is to a user depends upon differences in how they are able to use it.
I've tried to juxtapose the difference between perspective in italics and perception in bold in these sentences to help show how they are related. When considering interaction, you have to be aware of differences in desire, ability, understanding and previous experiences that each user will bring to that interaction.
This is an extremely broad question dealing with psychological paradigms like Perception where there's no definitive agreement. The perception mechanism is a high level function of brain, such as memory, attention span, language and others. These are alos known as executive functions, and the current status of science around this subject varies between really opposed theories. To make it even worse, perception can be used in physical devices, psychology point of views, visual and cognitive perspectives and many more. To put this in context, perception is always an hypothesis that is tested against previous bits of knowledge. Its main difference with perspectives is that the sum of perspectives helps to mold the perception (in sociology, it's the opposite, specially for marxism).
A very good read to understand these concepts is Flatland. Try to think in a bidomensional world and you'll have a 2-d perspective where you'll always see everything as a line. then add another dimension, or perspective, and you'll get the depth of objects. Figures became bodies. While in both cases we had a perspective and a perception, the second perspective is added to our experience to form our new perception of the world, now in a three dimensional environment.
All this long intro is to give just an extremely basic and simplistic view over a concept that is very long, broad, complex and complicated .
Going to an UX example, take a look to Evaluating Dual-view Perceptual Issues in Handheld Augmented Reality: Device vs. User Perspective to see a real world problem of user perception in UX.
A particular attitude towards or way of regarding something, it’s a point of view.
The true understanding of the relative importance of things, it’s a sense of proportion.
We must keep a sense of perspective about things we do.
A way of regarding, understanding, or interpreting something, it’s a mental impression.
We need to challenge many popular perceptions of old age.
It’s an intuitive understanding and an insight.
Putting oneself in other’s perspective changes the perception of life. It is the perception of our reality that governs the perspective towards our life. The question where do our perspectives come from? In fact they come from our perceptions."
The confusion between these two terms comes from the two meanings of perception:
"neuroscience" perception: a basic cognitive activity that consists on receiving the data input through the information channels (visual, audial, haptic etc), some initial parsing/pattern recognition of this input and basic brain's feedback on this information. Perception in this context mostly is meant as a minutely compound, a cross section of the current incoming data flow and reactions to it. "I perceive the sea as greyish today, with the slight hint of green."
"philosophical" perception: a point of view on some object or subject that consists of and implies mostly the "raw" perceived data. It can be more continuous than the physical perception.
"I perceive the sea as an endless source of inner balance."
Second meaning is where the concept of perspective meets the concept of perception as an adjacent term, with the difference that one's perspective will definitely include their personality traits and could include some analysis, context or bigger picture, whereas perception doesn't.
To me, perception is a first automatic reaction to things, while perspective is a more complex result of some further parsing. Moreover, perspective semantics suggest some distance from the object of perception. So perspective is a perception from a distance, with more things taken into account.
One's perception of a concept might be that it is nice or threatening, but their perspective, if developed, might differ radically.