Is it right that extrapulmo tb and miliary tb also spread by blood circulation in the body? and if does then what's the difference?

Major difference: During primary pulmonary TB the organisms gets into the blood stream and deposits small numbers of bacilli in multiple areas of the body. Any of these may blossom out into areas of extrapulmonic involvement. In miliary TB the blood stream disseminates large numbers of the TB organisms to virtually every area with all of them creating active disease and can be acutely life-threatening.

Both spread by blood: You are correct in that extrapulmonary and miliary TB are the same in that they both represent dissemination of TB through the blood stream. Miliary TB gets its name from the appearance on chest xray as distribution small spots which look like millet seeds. Approximately 15% of TB cases are extrapulmonary affecting lymph, pleura, uterus/testicles, bones, meninges, bowel, pericardium and skin.

Spread of TB: Extrapulmonary TB & miliary TB occur due to spreading of mycobacterium tuberculosis into the bloodstream from a primary focus of infection in the lungs. When the lung infection erodes into blood vessel, it spreads to sites other than lung (called extrapulmonary tb). Miliary TB is a specific type where TB spreads diffusely through entire organs (including lungs), producing small nodules all over.