Do different time signature have different tempos? If I take 4/4 as an example then I know I have to play 4 notes per measure. With 7/4 it is 7 n0tes per measure. Doesn't that mean that 7/4 is faster because you have to play more notes in the same amount of time? According to others tempo and time signatures are not the same, but I do not understand how. Sorry about the stupid question but I am self-taught and the only theory I know is scales, arpeggios and basic guitar techniques.

Help is appreciated.
not quite. the first number in a time signature tells you how many beats are in a bar. The second number tells you what type of notes are in a bar. so 4/4 will have four quarter notes in a bar while 7/4 will have seven quarter notes in a bar, so you will have more beats in a bar in 7/4 than in 4/4, but one won't be faster than the other unless you change the tempo.

hope that makes sense.
But won't I be picking faster with 7/4 in order to fit the notes into the bar?
not necessarily. in 4/4 you would count 1, 2, 3, 4 | 1, 2, 3, 4| etc etc
now in 7/4 you would count at the same pulse as you would in 4/4 like this:
1, 2, 3, 4, 5, 6, 7 | 1, 2, 3, 4, 5, 6, 7|

Why don't you grab a metronome that you can change the time signature with so you can hear the pulse and how they differ.
A 7/4 bar is longer in time than a 4/4.
Im a classical musician, and it will say when they change time sigs what gets the beat.
For example if it goes from 44 to 68 it will change from the quater gettin the beat to the dotted quarter gettin the beat.
A tempo is typicality written like this:
| = 60

The note drawn is a quarter note (thats 1/4) so a time signature 4/4 has 4 quarter notes. Read it like this: the duration of a quarter note (1/4) is exactly one second (60 beats per minute). Since 4 x 1/4 = 4/4, the duration of the bar will be 4 x 60 = 4 seconds.
If it's in 7/4: the first part remains --> the duration of a quarter note (1/4) is exactly one second. But 7 x 1/4 = 7/4 so the bar is 7 x 60 = 7 seconds.
This is true for any measure. Mind that is for example 12/8 the bar is divided in 4 and then in 3. So you won't use a 1/4 as bbm, but a 3/8 as time signature. See for yourself if you understand that

Explained in a mathy way, but I hope it makes sense If not just ask!