Hi , please what is the difference between randn and awgn , when adding white gaussian noise to get snr = 10dB , also I see difference in result when using snr function .

P_rms = rms(signal)^2; %

noisy_signal_1 = awgn(signal,10,'measured');

noisy_signal_2 = signal+0.1*P_rms*randn(L_t,1);

snr1=snr(signal,awgn(signal,10,'measured'))

snr2=snr(signal,noisy_signal_2)

var1=var(noisy_signal_1);

var2=var(noisy_signal_2);