woocommerce price problem

Hello,
I have a strange problem with woocommerce.
I import products in the shop. The price of the product is imported to the regular price field.

But in the shop somtimes is shown a different price.

Now i have found that there is a _regular_price field and a _price field.

I import to _regular_price but in the shop the _price is shown and this is somehow a different price.

But when i update the product (without making any changes) then the _price field is suddenly the same as the _regular_price field.

What is the difference between the _price and the _regular_price field? and how is the _price field filled with an price?

Hope someone can help me with this.