X-ray binaries are the most luminous candidates among the galactic X-ray sources. The variation in the X-ray intensities can be witnessed in many X-ray binaries on all timescales ranging from milliseconds to days or months. The orbital modulation of the X-ray intensities occurs due to various orbital phase dependent factors like the absorption and scattering of X-rays in the stellar wind of the companion, accretion streams, accretion disks etc. In transient systems X-ray outbursts occur when the accretion on to the compact object is enhanced around periastron passage. In this talk, I will discuss two type of X-ray variability in two HMXBs and the physical picture behind it. One of these is a persistent heavily obscured source and the other is a transient source with a Be type companion. First, I will present an unique partial eclipse seen in IGR J16393-4643. The orbital profile of the High Mass X- ray binary IGR J16393-4643 shows a dip in its X-ray intensity, which was previously interpreted as an eclipse. Unlike most eclipsing HMXBs, where the X-ray eclipses are about two orders of magnitude fainter compared to the out of eclipse emission, this particular eclipse like feature is narrow and partial, casting doubt if it is indeed an eclipse. We use a large number of Swift-XRT observations covering the entire orbital phase and our results indicate that this low intensity state might not be an eclipse, as previously thought but absorption in the stellar corona. Next, I will present a Be X-ray binary GRO J2058+42 that recently went through a Type-II outburst during March-April 2019 lasting for about 50 days. This outburst was detected with the operating all sky X-ray monitors like the Fermi-GBM, Swift-BAT and MAXI-GSC. Two NuSTAR observations were also made, one during the rise and other during the decay of the outburst. With this unique opportunity, we have analyzed the broadband characteristics of the pulsar for the first time and accretion torque characteristics of the pulsar over a range of X-ray luminosity.