Throughout/over the years, I have learned...

[thehammer]

When should I use 'over the years' and 'throughout the years'?

1- Throughout/over the years, I have learned a lot as an intern at my company.

 

[Barque]

In that sentence you need "Over".

I've learnt a lot over the years as an intern at this company.
I've learnt a lot over the years interning at this company.
Over the years as an intern at this company, I've learnt a lot.

People don't usually intern for years by the way. It's more likely to be a few weeks to a few months.