As delegates from Montgomery and Prince George's Counties admit, the one thing that truly matters in this year's General Assembly session is money.

For Montgomery County representatives, it is the money that less affluent jurisdictions want to take from the county's treasure trove. Delegation chairman Donald B. Robertson complained quite openly that "they are trying to rape us."

For Prince George's County delegates, the money that counts is the $15 million their county executive says is needed to balance the county's budget. County Executive Winfield M. Kelly Jr. told them that either a new tax structure must be adopted for the county or the property tax for home-owners will be increased by 26 cents rather than 15 cents.

These money problems have taken on a special sense of urgency since homeowners in both Washington suburban counties have besieged their delegates with complaints about recent property tax assessments. With voters asking for a reduction in their assessements, the Prince George's delegation will find it difficult to turn around and diplomatically adjust taxes to pay for Kelly's budget. And Montgomery County delegates feel they would be neglectful if they let one penny slip unnecessarily from their county.

Although the financing of the public school systems in the counties also is a crucial concern, the delegations have not written new legislation to answer the question but have settled for county representatives on the newly formed Maryland Commission on the Funding of Public Education.

Governor Marvin Mandel appointed the commission to devise one simple system for giving state aid to local school systems. Presently, aid is being parceled out through a dizzying variety of programs and, some delegates say, in an unfair manner.

A number of bills have been debated and struck down that would somehow alter the property tax assessment system. Prince George's and Montgomery County delegates are toying with ideas to somehow restrict the increase in property value allowed in one year. All are reacting to a minor tax revolt in their counties stemming from a two-year old statewide assessment program that was meant to eliminate inequities.

Some of these bills, like one introduced by Del. Gerald F. Devlin (D-Prince George's), would involve a statewide change that would cut property tax assessments on the average of 10 per cent.

Del. Lucille Maurer (D-Montgomery) has also cosponsored a statewide bill that addresses a particular concern of the counties: Cutting the cost of prescription drugs by revising the law in order to allow substituting non-brand name drugs for brand name drugs which are generically equivalent.