Hi,
Rule number-1 the most important when using AutoCAD is to keep your eyes on the command line and see what is going on when a command is being executed. That's where you have missed noticing what was happening.
When you selected the "circle, diameter" from RIBBON you drew the first circle by entering the diameter. But when repeated the command by right click and repeat "CIRCLE" you were specifying the radius and not diameter as you can see in the screenshot below.
If you always want to draw a circle by entering diameter then you can use this lisp🙂
(defun c:CD()
(command "_.CIRCLE" pause "_Diameter")
(princ)
)

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ವಿನೋದ್ ಕೆ ಎಲ್( System Design Engineer)

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