If I have knowledge of some musical terms such as intervals, chords, circle of fifth etc. but I don't know how to read or use staff paper but use piano sequence instead which I feel is pretty much same. is there anything that i can learn in staff paper or notation which I can't learn by using piano sequencer?
is it necessary to learn notation or how to read staff paper for making music?
Necessary? No. More ideal? Yes.
is there anything that i can learn in staff paper or notation which I can't learn by using piano sequencer?
Yes. Specifically it enables you to learn from an enormous amount of existing notated music and books that use notation. Those things aren't published in "piano sequencer" form so you wont be able to take advantage of them.
I think your premise that they're the same thing is wrong. They're both useful but for different things. I'd guess that most people (myself included) that know how to read music and also use DAW software end up using their ears and the sequencer grid in that context rather than looking at a staff notation view. But notation is still very useful in other contexts when learning.
That said, you don't have to feel bad for not knowing how to read music. Plenty of people, many legendary musicians even, get by without it. But I also wouldn't look for an excuse or talk yourself out of trying because it really can be helpful. You don't even have to read well (ex. sight-read) to still benefit. Simply knowing enough of the basics to slowly pick up a new tune would be a big help.
I think no.
You certainly don't need to know how to read musical notation in order to play music on an instrument. Many people learn by ear and, steeped in a particular idiom, make music entirely without reading it or writing it down.
I don't know much about sequencers, but I just tried doodling with one online. It looks to me like you could use that without reading music as well. To me, it looks just like a carousel organ or organette music strip. Dots and dashes of varying lengths equate to different tones and time values. Seems pretty intuitive.
Ultimately, it comes down to the fact that sheet music and all its theory is not a requirement for learning music, BUT sheet music and music theory does help improve one's understanding of music. For example, sheet music makes changes in the key obvious with accidentals, whereas otherwise one wouldn't have much of a warning. Also, composing without understanding is not impossible, but this is the biggest area where understanding helps a lot. Essentially, music theory can help one see patterns in music and apply them in one's own creations, where without it one would have to adopt a more trial-and-error strategy.