What is the difference between preflop ranges and preflop strategy charts?

Ranges tell you the percentage of poker hand combos you have at that part of the game tree, 
whilst strategy charts tell you at what frequency you should take an action.

For example: 
8max 20bb, UTG opens.

BTN either flats AQs 42% of the time or goes all in 58% of the time. Here they flat (so they have 42% of the max possible AQs combos).

BB goes all in, UTG folds.

Action on BTN: 
The BTN calling range for AQs is 42% (as they don't have all possible combos of AQs, as they would have gone all in with AQs 58% of the time vs the UTG open)
The preflop chart shows Call 100% for AQs as in this spot at this moment, whenever BTN has AQs they should call (for all combos of AQs that BTN has, they should be called at 100% frequency).

Preflop ranges are useful for both preflop and postflop work in PioSOLVER, whereas preflop charts are used for preflop strategy advice only.
RangeConverter online range viewer allows you to view both preflop ranges and strategy charts (see details Range Reg and Range Pro). You don’t need to have any GTO poker solver to study opening ranges or 3bet range charts.

For more background information on ranges in general, check out this guide to poker ranges and hand reading.
Head to https://rangeconverter.com/users/sign_up, sign up and use the free demo to view the preflop charts and ranges.