Are Slicing and Splitting same?
What is difference between splitting and slicing user stories? Are they same or different in some way?
Yes and No!
Yes: Normally slicing and splitting are used interchangeable and mean nothing more than breaking user stories down to smaller user stories that contain an independent amount of work that can be developed, tested, run.
No:In some companies they make a destinction between splitting (which still is the breaking down of larger user stories into smaller user stories) and slicing.
Where slicing is cutting the smaller user stories into tasks, mostly based on vertical splitting (front-end, business logic layer, back-end, services, database,etc...)
So it's best to ask in the company where you work what their "lingua franca" is.
Find out why splitting or slicing happens at all. Is there a prescriptive requirements set which people are trying to break down reductively into chunks that can be accomplished in Sprint timescales?
Scrum is not a reductionist approach to requirements management, it is an empirical and experiential one of learning to build the right thing at the right time.
Splitting and slicing is not necessarily wrong, but what assumptions are then being validated? Where are the experiments?
Many people feel that in order to refine Product Backlog Items, it requires them to be split/sliced/broken down/right-sized. In reality, items can be refined without that activity. I say "that activity" because the words used to describe are varied but the activity and result are pretty much the same. Don't get hung up on the vocabulary, look at the work and result.
You will get different answers to your question depending on the experiences the person answering has. I have used a large number of descriptors for the activity of rephrasing a problem into workable descriptions.