Recently just bought the X3 Terran War Pack. Having never played any of the X3 Series, which of these two should I play, in terms of the most included content. Apparently Albion Prelude is an expansion to Terran Conflict, but does that mean that all the content is added to TC, or are they still two completely different games?

Thanks for any info.

They are two very similar games. Essentially, Albion Prelude is a sequel that introduces a number of new ships and features such as the stock exchange, and has its own plotlines. However, since the plots are not the focus of the game you would not be missing out on much by going straight to Albion Prelude. Or, you could do what I have done and install the Terran Conflict plots for Albion Prelude mod, at which point it basically contains all the Terran Conflict content, in addition to the new stuff.

There has been re-balancing and tweaking done to AP.

Hardrada's solution is probably the best if you want to experience the full "story" or campaign of X3:TC. X3:AP is not only an add-on, but also comes with engine upgrades that make the game more enjoyable on modern hardware, such as increased visibility range.