if i go with Sigma 50mm F1.4 art and use it at F1.4 and shoot the subject from lesser distance than 85mm f1.8 (keeping the same field of view and frame) does 50mm f1.4 will produce the same or more bokeh then 85mm f1.8?
It seems you are confusing the amount of blur with the quality, or characteristics of that blur. Bokeh is a term that is only concerned about the latter, not the former.
No two lens designs will produce the same bokeh, even if they are both used with the same focal length and aperture. For a specific example, please see below regarding the EF 85mm f/1.2 L II and the EF 85mm f/1.8. When both are used at f/1.8 to photograph the same scene from the same camera position the amount of blur they produce in the background will be very similar, but the way that blur appears will be starkly different!
Your other confusion stems from a lack of understanding regarding perspective. If you use a 50mm lens and move closer to the subject to get the same subject size, the framing of the background will change! Things in the background that will be visible on the edges in the 50mm shot will not be visible when you back up to keep your subject the same and use an 85mm lens.
The scale is highly exaggerated, but hopefully communicates the concept that different angles of view show more or less of the background at the same subject size.
For a more comprehensive look at this issue, please see: Is there a difference between taking a far shot on a 50mm lens and a close shot on a 35mm lens?
Why is the background bigger and blurrier in one of these images?
On one side i need all go to lens for indoors & travel (some landscape photography) i also need good bokeh for portrait photography.
Unfortunately, these requirements are somewhat diametrically opposed.
What most of us consider "good" bokeh, in terms of the quality of the out-of-focus highlights, results from lens design that leaves field curvature and/or spherical aberration undercorrected or uncorrected. That means such a lens won't be the best candidate for other types of photography, such as landscape or architecture, when we want good sharpness all the way to the edge of the frame.
The classic example of this is the Canon EF 85mm f/1.2 L II. What gives it such great bokeh is the uncorrected field curvature it demonstrates. This makes it a totally inappropriate lens for doing flat reproduction work or for shooting flat test charts because the field of focus on the edges and in the corner will be a considerable distance in front of the flat subject when the center of the lens is perfectly focused on it. If you want to shoot a perfect photo of a flat test chart, the $350 EF 85mm f/1.8 absolutely cleans the floor with the $2,000 EF 85mm f/1.2 L II. But when you want that mesmerizing bokeh on the edges of a portrait there's nothing like the 85/1.2!
On the other hand, a lens that is good for landscape or architectural photography has a much flatter field of focus that makes the bokeh of the out of focus areas look harsh or "busy."
