What's the difference between Data and Internal Storage? I came across installing ROMs, but I can't install it because I need to wipe some things ...

It told me to wipe / do a factory reset ...

Then, when I go to the Wipe Section of the TWRP Recovery, clicked on Advanced Wipe, I noticed that there is Data, and there is Internal Storage.

Here's a picture of that: (from androidtipsandhacks)



TWRP told me that Data, Cache, and Dalvik is the only wipe that I need.

Will wiping Data remove my apps, music, photos, videos, and app data?



Answer:

Data

Data is your user apps (installed from Google Play Store, or with an *.apk) and its app data.&nbsp;&nbsp;It is stored on /data.


Your user apps is stored on /data/app.
Your apps' data is stored on /data/data.


NOTE: You must be rooted to see the contents on /data/ ...

Therefore, if you wipe your data, it might also delete your user apps, and its app data, but excluding your music, photos, videos, etc.

Internal Storage

On the other hand, Internal Storage is actually the storage where your other data are saved, such as music, photos, videos, other app data, downloads, etc., and is usually stored on /storage or /sdcard.

NOTE: /sdcard is different from your external SD Card.


Music is saved on /sdcard/Music.
Photos are saved on /sdcard/DCIM.
Videos are saved on /sdcard/Videos.
Other app data are saved on /sdcard/ (App Folder).


Other apps choose to store their app data on /sdcard/ ..., such as Minecraft: /sdcard/games.

Downloads are saved on /sdcard/Downloads, and can be easily found if you have the Downloads app.
Two relevant aspects before answering your specific questions :


You are planning to install a new ROM
The device is going to be with you so you are not bothered about wiping all personal traces ( like you would be if you are planning to sell)
See What should I wipe in TWRP? from official TWRP help . That would take care of your needs for installing a new ROM



  If you are switching ROMs (changing from one ROM to a completely different one) then you should perform a factory reset. A factory reset wipes data and cache (which includes dalvik cache). A factory reset will also wipe sd-ext and android_secure if your device has those items. 99% of the time, this is all that you need to wipe and you only need to do it once, not three times as some people would lead you to believe.


(Emphasis supplied)

factory-reset is equivalent to Wipe data,cache, dalvik. It will not remove your pictures . See Firelord's answer which has other useful references as well


  ...Factory Reset would remove everything under /data (excluding /data/media which serves as emulated storage available through /sdcard as internal SD card)...




  What's the difference between Data and Internal Storage?



Data is what is contained in the / datapartition. Internal storage world refer to the entire device directory structure and what is contained in them as well


See What happens when I wipe the internal storage of a device using TWRP?
Also TWRP help explains further



  ....you may have options for wiping internal storage, external storage, sd-ext, android_secure, and/or an option for formatting data. There's almost no reason that you would ever need to use these items....


(Emphasis Supplied)