I have an old Roberts RD-60 FM radio with a jack port at the top with a headphones icon and another jack port at the back called "Line Out".
I know nothing about electronic circuits, so, based on images like this
https://www.radios-tv.co.uk/wp-content/uploads/2019/09/psucct.jpg?vu003d1568578522
is anyone able to let me know if there is any difference between these two jack ports, typically their power output?

Thanks

 

That's not the Roberts radio, that is something else, probably a mains radio or TV.
Line out is usually 1V signal to feed into a separate amplifier, headphones output will be more powerful .

 

At least there is a difference: when plugged to "Line Out", the speaker of the radio keeps playing, so for my planned use, I'll use the headphones port.

Thanks for your answer.

 

Line out is usually 1V signal to feed into a separate amplifier

I was going to say that, but Dave said before me.

Yes, line out is for connecting to other devices. You'll find Line Out (LO) for connecting a tape deck or an external amplifier. It's an uncontrolled output. It's not affected by volume, base, treble or balance settings. Headphones (the jack) is fully controllable with volume, balance and tone settings. You don't want that for connecting to an amp or recorder - or other.

 

In theory the Line Out may also have lower distortion.