Does Registers and RAM are same kind of memory?
There is DRAM which uses a capacitor to store a charge to represent the stored bit. A row of transistors is used to connect a row of capacitors to the read/write circuitry to put the data into a set of latches to read it and also feed it back into the row to refresh the capacitors' charge which was depleted into the latch's input. 

The capacitors will self discharge over time so each row needs to be refreshed periodically. In most DRAM you can only read or write a single row at a time. 

This type is used for the main RAM because it is cheaper in silicon per bit. 



Then there is SRAM which uses flipflops to store the data which takes a half dozen transistors per bit. It has a constant output available so can be read at any time using a MUX, instead of having to wait until the proper row can be selected. 

This type is used internally for nearly everything on the cpu (including caching the current row in DRAM) because it is much faster.