Etstimate AR(1) coefficient in Matlab

Hello, I have a time series data of GDP of US during 1980-2017 yearly.

I assume that GDP follows an AR(1) process, like: y(t) = rho*y(t-1) + e(t)

Now I want to estimate the coefficient rho. I was searching and found 2 ways:

1- use the command ar: ar(y,1) (as instructed here: https://www.mathworks.com/help/ident/ref/ar.html)

2- use the Arima estimation: md1=arima(1,0,0) Estmd1 = estimate(mdl,y) (as instructed here: https://www.mathworks.com/help/econ/arima.estimate.html) I tried both way and got different result on the estimation of coefficient rho. Could you tell me which way is correct?

Thanks!

[mirewuti muhetaer]

As far as i know, ar(y,1) uses least sequared estimation (OLS) approach while estimate() funciton uses MLE approach. So the result is definitely different.