Predicted Trend line (ytrend) vs. Regression line for time series data

[ajames2020]

Are these two lines the same? This is based on a segmented regression that I'm doing. I'm trying to use two separate methods to create the plots:

1. Do separate regression lines by using sgplot and the "group" option for under regression.

2. Generating values for ytrend using proc autoreg, then plotting the trend line. 

The lines from 1 and 2 above seem to fit the points differently. Option 1 gives me a better fit. If I'm interested in connecting the two regression lines generated in option (1) above, how would I do that? (I'm trying to show a level change in my interrupted time series analysis.

[smantha]

A regression line is different from a trend line,Though both can be correlated some times. This is more evident in time series plots. For a time series the following are how things are looked at

Y=intercept+seasonality(seasonal patterns)+Other causals

as an example if you are measuring sales due to an advertising campaign Other causals represent your marketing actvity and Y is the sales response, then your intercept+seasonality must be able to capture trend.