The first thing we should cover is the difference between E Standard, Drop D, Drop C, and what bands use what tuning. Standard is what most guitarists use (standard for a reason):
Now, power chords in a standard song might look like this:
You can play this chord anyway you desire, but I find it easiest to put my pinky over the A and D strings on 5 and put my index finger on the 3. If you can play this, most likely, you can play drop D and C.
However, this tutorial is for bands that use Dropped Tunings some examples:
Escape The Fate and Falling In Reverse: Drop C
Three Days Grace and Papa Roach: Drop D
Avenged Sevenfold: Drop D
Bullet For My Valentine: Drop C
Drop DDrop D is the same exact tuning as standard, except, the low E string is tuned down to a D:
Bands utilize this trick to make power chords easier. Instead of:
it can be played as:
I play these by pressing my middle finger down on them.
If you are tuned to drop D however, any song in standard on the low E string, must be played 2 frets higher.
Example of a drop D song:
Avenged Sevenfold: "Nightmare" (Rhythm Guitar chorus)
All chords are strummed 8 times
The first power chord cannot be achieved in standard (all open). This presents many opportunities such as palm open mutes.
Another downfall to Drop D is that your normal chords that use the low E string cannot be played.
If a song is set in standard, 99% of the time you have to play it in standard. New bands like to play in drop D for a more full tone and easy access to power chords.
This is where your post-hardcore bands come in. Drop C is the same exact concept of Drop D except every note sounds 2 frets lower than in drop D.
In drop D, an all open chord in drop C is impossible.
Drop D = Drop C
Drop C can copy any drop D note (except on 23rd and 24th frets). Drop D cannot copy any notes on an open, 1st, or 2nd fret power chord.
Escape The Fate - "Situations" CGCFAD
This song would be impossible to play correctly in Drop D because the
chord cannot be played.
Soloing in different tunings
Soloing in drop D is the same as Standard as long as you aren't using the E string. if you are, you have to add 2 frets.
Soloing in drop C
To solo in a drop d song while playing drop D, you must add 2 frets to everything. Pretty much same rule for the power chords.
Hope you understand the difference now.